1. health and fitness
2. disease
3. cancer

NHS Breast Screening
Evidence resource on information about the
NHS Breast Screening Programme
Informed Choice about Cancer Screening
September 2013
Contents
1.
Introduction ................................................................................................................. 3
2.
What is breast cancer? ................................................................................................ 4
3.
What is breast screening? ......................................................................................... 13
4.
What happens at the breast screening appointment? ............................................. 17
5.
What are the possible results of breast screening? .................................................. 21
6.
What happens if the tests show breast cancer? ....................................................... 25
7.
Treatment for women diagnosed with invasive and non-invasive breast cancer .... 26
8.
How good is breast screening at finding cancer? ...................................................... 27
9.
Weighing up the possible benefits and risks of breast screening ............................. 28
10. Sources of more information about breast screening .............................................. 37
Acknowledgments............................................................................................................. 38
Glossary ............................................................................................................................. 39
Notes on methods used to compile this evidence resource ............................................ 44
References ........................................................................................................................ 45
1
Figures
Figure 1: Frequency of breast cancer in UK women by age at diagnosis ........................... 9
Figure 2: A woman having a mammogram with a mammographer ............................... 20
Figure 3: Outcomes for 100 women attending breast screening at a given time. ........... 22
Figure 4: The difference between a normal milk duct, non-invasive breast cancer and
invasive breast cancer ...................................................................................................... 25
Figure 5: Benefits and risks of breast screening, as estimated by the Independent UK
Review of Breast Screening .............................................................................................. 31
Figure 6: Benefits and risks of breast screening as estimated by the Independent UK
Review of Breast Screening (alternative version) ............................................................. 32
Figure 7: Weighing up the main benefit and risk of breast screening ............................. 34
2
1. Introduction
The NHS offers breast screening to women aged 50 to 70 every three years. It aims to
detect breast cancers at an early stage, before they have started to cause symptoms,
and thereby to save lives from breast cancer. Breast screening does, however, have
some risks. The main risk is that some women who have screening will be diagnosed
and treated for breast cancer that would never otherwise have been found, or caused
them harm.
This document provides information on the benefits and risks of breast screening and
what to expect at an NHS breast screening appointment. It is for anyone who would like
more detailed information than is provided in the leaflet sent to women invited for NHS
breast screening. People who may find this information helpful include women who
have been invited for NHS breast screening (and their partners, family, or carers) and
health professionals.
This document has been structured in a similar way to the leaflet sent to women invited
for NHS breast screening to make it easier to find the evidence relating to each section
of the leaflet.
Some complex and scientific words throughout this document have been put into bold
print like this. These words are explained in the glossary on page 39.
3
2. What is breast cancer?
Breast cancer happens when cells in the breast start growing in an irregular,
uncontrolled way. As the cancer grows, cancer cells can spread to other parts of the
body and this can be life-threatening, if it is not treated.
How common is breast cancer?
Breast cancer is the most common cancer among women. Around 1 in every 3 cancers
diagnosed in women is a breast cancer.1 About 1 in 8 women in the UK will develop
breast cancer in their lifetime.2
In 2010 in the UK, 55,329 women were diagnosed with breast cancer,3 4 and 11,556
women died from breast cancer.5
Men can get breast cancer, although this is much less common. In 2010, 375 men were
diagnosed3 4 with breast cancer in England and 77 men died of this cancer.5 Men are not
invited for screening by the NHS Breast Screening Programme.
The risk of breast cancer increases with age, particularly after age 50. About 4 out of
every 5 breast cancers diagnosed are in women over 50 years old.3 4
How does breast cancer start?
Like the rest of the body, the breasts are made up of cells, which together form what is
called tissue. Milk is made in parts of the breast called lobules. It then flows to the
nipple through tubes, called milk ducts.
The space between the lobules and ducts contains blood vessels and lymph vessels.
Blood vessels carry oxygen to and from the cells of the breast. Lymph vessels carry a
fluid called lymph to lymph nodes near the breast (usually in the armpit). Lymph nodes
filter lymph and help protect the body from disease by removing unwanted things, such
as bacteria and cancer cells.
Most breast cancers begin in the cells that line the milk ducts.6 Normally, cells grow,
divide, die, and get replaced in an orderly way. In cancer, the cells start growing in a
disorderly, uncontrolled way, and much more quickly.
How does breast cancer spread?
As the cancer cells grow, they may spread from the milk ducts into nearby tissue. If
these cells enter the blood vessels or lymph vessels, they can be carried to other parts
of the body and start growing there. When a cancer spreads, this is called metastasis;
this is when breast cancer becomes life-threatening.
4
What are the types of breast cancer?
There are several types of breast cancer. The main types are:

Ductal breast cancer: cancer that starts in the ducts of the breasts. This is the
most common type of breast cancer.7

Lobular breast cancer: cancer that starts in the lobules of the breast. This is the
second most common type of breast cancer.7

Inflammatory breast cancer: a less common cancer that blocks the lymph
vessels in the skin of the breast. This makes the skin look pitted or dimpled, like
orange peel. The skin may also feel warm and often looks red. Some women with
this kind of breast cancer will develop an obvious lump in the breast but others
will not. This type of cancer can develop and spread quickly.8

Paget’s disease of the breast: a less common cancer that affects the skin on and
around the nipple. Signs of Paget's disease can include itching, redness, and
flaking of the skin.9 In its early stages, Paget's disease is often confused with
eczema and other skin conditions. Women with Paget's disease often have
cancer within their breast as well.
What are the stages of breast cancer?
Once a woman is diagnosed with breast cancer, a breast cancer specialist will do a
number of tests to work out how advanced it is. Breast cancer specialists usually use
stages to describe how advanced a cancer is. Knowing the stage of a breast cancer can
help a woman and her doctor decide on the best treatment.
There are five stages of breast cancer. These range from stage 0 (the earliest stage,
when the cancer has not spread from where it started) to stage 4 (the most advanced
stage, where it has spread around the body).10
To work out what stage a cancer has reached, doctors look at three main things:

How big the tumour (lump) is, and whether it has spread from the breast tissue
into the nearby skin or chest wall.

Whether the breast cancer has spread to the lymph nodes, how many, and
which ones.

Whether the breast cancer has spread from the breast to other parts of the body
beyond the nearby skin, lymph nodes, or chest wall.
5
Stage 0
This is the earliest stage of breast cancer. It is also called non-invasive cancer. Most
stage 0 cancers are a type called ductal carcinoma in situ (DCIS). Cancer cells have
formed within the ducts of the breast, but they have not grown into (invaded) the
surrounding tissue or lymph nodes.11 The cancer may eventually grow into the
surrounding breast tissue or spread to the lymph nodes and other parts of the body in
the future, or it may not.
Doctors cannot tell whether a woman with DCIS will have a cancer that will grow and
spread if left untreated.12 13
Lobular carcinoma in situ (LCIS) is also described as stage 0, although it is not usually
thought of as cancer. It means some of the cells in the lobules of the breast are
abnormal. Women with LCIS have an increased risk of eventually getting cancer in either
breast.12
Stage 1
This is also known as early stage invasive cancer. Stage 1 breast cancer has grown out
of the ducts or lobules into the surrounding breast tissue. The tumour, if present, is
small (2 centimetres or less across) and the cancer has not spread to the lymph nodes,
or only very few cancer cells are in the lymph nodes.10
Stage 2
This is invasive cancer. Stage 2 breast cancers can be divided into three main categories:

the tumour measures less than 2 centimetres across and has spread to lymph
nodes under the armpit.

the tumour is between 2 centimetres and 5 centimetres across whether or not it
has spread to the lymph nodes under the armpit.

the tumour is larger than 5 centimetres across but has not spread to any lymph
nodes.
6
Stage 3
This is invasive cancer that has spread further than stage 2. Stage 3 breast cancers are
larger than 5 centimetres across (if a lump is present), or have cancer cells in the lymph
nodes, or are growing into nearby areas. Smaller tumours can be classed as stage 3
cancers if10:

the cancer has spread to many lymph nodes in the armpit or has matted
together the lymph nodes under the armpit, or

the cancer has spread into the chest wall or the skin, or

the cancer has spread to lymph nodes above or below the collarbone (clavicle) or
near the breastbone (sternum).
Inflammatory breast cancer is usually stage 3 or 4 when it is diagnosed.14
Stage 4
This is advanced invasive cancer, also known as metastatic cancer. Stage 4 cancer is any
breast cancer that has spread beyond the breast, lymph nodes, or nearby areas to other
parts of the body.10 The parts of the body most likely to be affected are the bones,
lungs, liver, more distant lymph nodes, or brain.15
What are early, locally advanced, and advanced cancers?
These names are another way that doctors describe how advanced an invasive cancer
is16:
Early invasive breast cancer: This means the cancer is still fairly small (around 2
centimetres or less) and hasn't spread beyond the breast and nearby lymph nodes.
Locally advanced breast cancer: This means the cancer is in a large part of the breast
and may also be in the lymph nodes. However, it hasn't spread to other parts of the
body.
Advanced breast cancer: This usually means the cancer has spread to other parts of the
body. It can also mean that the cancer hasn't spread but has grown directly into tissues
close to the breast and cannot be removed through surgery.
What is the grade of a breast cancer?
Doctors also look at how much the cancer cells resemble normal breast cells when
viewed under a microscope. This is called grading (see grade). Doctors usually grade
cancers as 'low grade', 'intermediate grade', or 'high grade'. Low-grade cancer cells look
similar to normal breast cells. High-grade cancer cells look very different to normal cells.
Higher grade cancers tend to grow more rapidly and spread faster than lower grade
cancers. Cancer grade can also be described as a number between 1 and 3. A lower
number means a lower grade.15
7
What are the symptoms of breast cancer?
The symptoms of breast cancer are9 17:

A lump or thickening in the breast or the armpit.

A change in the nipple. The nipple might be pulled back into the breast (known
as an inverted nipple), or change shape. There may be discharge from the nipple,
such as blood or other fluid, or there may be a nipple rash that makes the nipple
look red and scaly.

A change in how the breast feels or looks. It may feel heavy, warm or uneven, or
the skin may look dimpled. The size and shape of the breast may change.

Pain or discomfort in the breast or armpit.
Women who experience any of these symptoms should make an appointment to see a
GP straight away. These symptoms do not necessarily mean a woman has breast cancer.
But if she does, being diagnosed and treated at an early stage may mean she is more
likely to survive breast cancer.
About 32 in 100 women with breast cancer are diagnosed through screening, when they
do not have symptoms. The remaining 68 women in 100 are diagnosed because they
have symptoms, in other words, changes to their breasts.18
What increases the risk of breast cancer?
Age
The chance of getting breast cancer increases with age; the older a woman is, the more
likely she is to get breast cancer. About 4 out of 5 women diagnosed with breast cancer
are older than 50.3 4 19-27 Figure 1 shows how the frequency of breast cancer changes by
age group at diagnosis in the UK (it shows the average number of new breast cancers
diagnosed each year and the number per 100,000 women in that age group: this is
known as age-specific incidence.3 4 19-28 The incidence of breast cancer increases with
age. It is high in the age group invited for screening because screening means that some
breast cancers are diagnosed earlier. If there were no breast screening, some of the
cancers diagnosed in the screening age group would be diagnosed later when women
reach their 70s and 80s.
8
Figure 1: Frequency of breast cancer in UK women by age at diagnosis
10000
500
9000
450
8000
400
7000
350
6000
300
5000
250
4000
200
3000
150
2000
100
1000
50
0
0
Year
0-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
65-69
70-74
75-79
80-84
85 and
over
Age group at diagnosis
Number of cases
Incidence rate
*The age-specific rate of new cases (incidence) presented in Figure 1 is standardised to the UK population. This means that
age-specific incidence rates are calculated separately for each of England, Wales, Scotland and Northern Ireland, and are
then weighted according to their respective population sizes before being added together to produce an incidence rate for
the entire UK. This is done to account for the different age structures of the populations of the four countries making up the
UK.
Family history and inherited genes
Most breast cancers are not due to family history or inherited breast cancer genes. This
means that women who have no family history of breast cancer are still at risk. Many
women with breast cancer do have relatives with breast cancer, but often this is
because breast cancer is so common, not because it is inherited.
However, a family history of breast cancer does increase the risk. The chance of a 20
year old developing breast cancer by the time she is 80 is about 8 in 100 if she has no
close relatives with the disease, 13 in 100 if she has one close relative with the disease
and 21 in 100 if she has two or more close relatives with it.29
Some women have inherited genes that make breast cancer more likely. About 10 in
100 cases of breast cancer in Western countries like the UK are due to inherited genes. 30
The most important genes that increase breast cancer risk are BRCA1 and BRCA2, which
are estimated to cause between 3 in 100 and 7 in 100 breast cancers.31 Studies show
that women with a faulty BRCA1 gene have a 65 in 100 chance of getting breast cancer
by age 70. Those with a faulty BRCA2 gene have a 45 in 100 chance.32
9
Age-specific rate of new cases of breast cancer per 100,000 women
Average number of new cases of breast cancer
Average number of new breast cancers diagnosed and age-specific rate* of new breast cancers
diagnosed per 100,000 women each year between 2007 and 2011.
Lifestyle
Being overweight or obese: Being overweight or obese can slightly increase a woman's
risk of getting breast cancer once she has past the menopause.33 This could be because
fat helps the body make oestrogen, and oestrogen seems to promote the growth of
some breast cancers. In a UK study with more than 1.2 million women aged 50 to 64,
researchers looked at how many women developed breast cancer over an average of
five years, based on their weight. About 4 in 1,000 healthy-weight women developed
breast cancer, compared with 5 in 1,000 women who were overweight, and 6 in 1,000
women who were obese. The researchers estimated that women who were overweight
were 10-20% more likely to develop breast cancer than healthy-weight women, and
women who were obese were 40% more likely to develop breast cancer.34
Drinking alcohol: Drinking alcohol can increase the risk of breast cancer.35 The more a
woman drinks on a regular basis, the greater her risk. One review of 53 studies found
that women who had about four drinks per day increased their risk of breast cancer by
about a third, and women who drank around five or more drinks a day increased their
risk by almost half. The authors of the review estimated that about 9 in 100 women who
do not drink will develop breast cancer by age 80, compared to about 11 in 100 women
who have 3 alcoholic drinks per day, and 13 in 100 women who have 6 or more alcoholic
drinks per day. 36 Another study estimated that around 6 in 100 breast cancers in the UK
in 2010 were linked to alcohol.37
Being inactive: Doing little or no physical activity is linked to an increased risk of breast
cancer. A review found that, overall, the least active women had a 25 percent higher risk
of breast cancer, compared with the most active women.38 A UK study estimated that,
in 2010, more than 3 in 100 breast cancers among women after the menopause were
linked to too little exercise (less than 150 minutes of moderate activity per week). 39
Eating a high-fat diet: Eating a lot of high-fat foods seems to increase a woman's risk of
breast cancer, particularly if she eats a lot of saturated fat.40 In a study of nearly 320,000
European women, those who ate the most saturated fat were 13 percent more likely to
develop breast cancer than those who ate the least.41 Saturated fat is found in foods
such as red meat, butter, and cream.
Hormones
Starting periods early or going through the menopause late: Both of these increase the
risk of breast cancer, probably because the female hormone oestrogen promotes the
growth of some breast cancers.42 If a woman starts her periods early (before age 11) or
goes through the menopause late (after age 54), then she will have higher levels of
oestrogen in her body for longer.30 43 44
10
Taking hormone replacement therapy (HRT): Some women take HRT to help with
symptoms of the menopause. Women may take oestrogen-only or combined oestrogen
and progestogen HRT. HRT increases a woman’s risk of breast cancer while she is taking
it, and for up to five years after she stops.45 For every 1,000 women taking combined
HRT for 10 years, about 19 more women will get breast cancer during this time than
they would have if they did not take it. For every 1,000 women taking oestrogen-only
HRT for 10 years, about 5 more women will get breast cancer during this time than if
they did not take it. Within five years of stopping HRT, a woman's risk of breast cancer
drops to the same level as for a woman who has not taken HRT.46
Taking oral contraceptive pills: Studies don't provide a clear answer about whether
taking the contraceptive pill increases the risk of breast cancer.47 Some studies have
found that a woman's risk of getting breast cancer increases by a small amount while
she is taking the pill.48 But once she stops taking it, this extra risk goes away over the
next 10 years. Other studies have found that taking the pill doesn't seem to increase the
risk of breast cancer.49
Other breast conditions
Hyperplasia: This is an overgrowth of cells in the breast. It isn't cancer but it raises a
woman's risk of breast cancer. If the cells look close to normal, this is called ‘usual
hyperplasia’. Overall, women with usual hyperplasia are about twice as likely to get
breast cancer as women without hyperplasia. If the cells look abnormal, this is called
‘atypical hyperplasia’. Women with atypical hyperplasia are between four and five times
more likely to get breast cancer as those without hyperplasia.50-53
Lobular carcinoma in situ: Women with lobular carcinoma in situ (LCIS) have a raised
risk of getting breast cancer in either breast. It is most likely to occur in the breast where
LCIS was found. It isn't certain how many women with LCIS develop breast cancer, as
different studies have had different results. One review of studies found that between 4
and 9 women out of 100 diagnosed with LCIS develop breast cancer within the next five
years.54 55
Previous breast cancer: Women who have had cancer in one breast have an increased
risk of getting a new cancer in the other breast or in another part of the same breast. 5658
Dense breasts: Breasts that contain a low percentage of fatty tissue are described as
being dense. Having denser breasts raises the risk of breast cancer. Women with the
densest breasts are four to six times more likely to develop breast cancer than those
with the least dense breasts.59-61
11
Birth and breastfeeding
Older age at birth of first child: This increases a woman's chance of getting breast
cancer, although the reasons why aren't clear. Women who never have children also
have an increased risk. 44 62 In one study, which followed women up for up to 27 years,
about 1 in 100 women who had their first baby around the age of 23 developed cancer,
compared with about 4 in 100 women who gave birth around the age of 34, and nearly
5 in 100 who gave birth around the age of 38.63
Not breastfeeding, or not breastfeeding for very long: Breastfeeding reduces the risk of
breast cancer. The longer a woman breastfeeds, the lower her chance of getting breast
cancer.64 65 One study estimated that around 3 in 100 breast cancers in the UK would be
prevented if women breastfed each of their children for six months or longer.66
Radiotherapy
A woman's risk of breast cancer is higher if she had radiotherapy to her chest as a child
or young adult.67 Radiotherapy is often used to treat other cancers, such as Hodgkin's
disease, non-Hodgkin's lymphoma, and leukaemia.68 The younger a woman was when
she had radiotherapy, the higher her chance of developing breast cancer. The risk is
especially high for women who had radiotherapy at a young age for Hodgkin's disease,
as this type of cancer is treated with a higher dose of radiation.69
12
3. What is breast screening?
Breast screening uses an X-ray test called a mammogram to check the breast for signs of
cancer. It can spot cancers that are too small to see or feel.
What is the purpose of breast screening?
The purpose of breast screening is to reduce the number of women who die from breast
cancer. Screening does not prevent breast cancer. In breast screening, mammograms
are used to find breast cancers at an early stage when they are too small to see or feel.
Women with breast cancer diagnosed at an early stage are more likely to survive breast
cancer than women diagnosed at a later stage.
What is the NHS Breast Screening Programme?
All women aged 50 to 70 in England are invited for breast screening every three years.
When a woman is invited for screening, she receives an invitation in the post from her
local screening unit. Her invitation letter gives her a date, time, and location for a
mammogram. There are about 80 screening services throughout England.70 The units
can be mobile, in a hospital, or at a convenient location in the local community, such as
a shopping centre.
When a woman receives an invitation to breast screening, she has a choice. She can
attend the appointment, reschedule the appointment if it's not convenient, or decide
not to have breast screening. To help her decide, the screening unit will enclose a leaflet
along with the invitation letter. This leaflet gives information about the benefits and
risks of breast screening and what it is like to have a mammogram.
The NHS Breast Screening Programme Age Extension Trial
In England, the NHS Breast Screening Programme is currently inviting some women aged
47 to 49 and 71 to 73 to have breast screening. This is being done as part of a
randomised controlled trial of the benefits and risks of breast screening in older and
younger women.
As part of the trial, half of the women aged 47 to 49 and 71 to 73 in certain parts of the
country are being randomly selected and invited for breast screening, in addition to the
screening carried out for women aged 50 to 70. Over 10 years, researchers will compare
breast cancer diagnoses and deaths in these women, to those offered screening from
ages 50 to 70 only. The aim of the study is to find out more about the benefits and risks
of offering breast screening to women in these age groups.71 72
The reason for the study is that little is known about the balance between the benefits
and risks of offering breast screening to women aged 47 to 49 and 71 to 73. For more
information about this, please see the sections on benefits and risks on page 28.
13
Why aren't women below the age of 50 offered breast
screening?
Younger women aren't offered breast screening because:

Their risk of breast cancer is lower. 4 out of 5 breast cancers occur in women
over the age of 50. In 2010, about 30 in every 100,000 women under the age of
45 were diagnosed with breast cancer. This is compared to about 353 in every
100,000 women aged 45 and over.73 74

Younger women's breasts tend to be denser than older women’s, which can
make mammograms more difficult to read and less accurate. After the
menopause, women's breasts contain more fat, which means they are less
dense. Most women go through the menopause around the age of 50.75 76

Starting screening at a younger age would mean a woman would have more
mammograms over her lifetime. This would increase her exposure to radiation
from the X-rays. The radiation dose used in mammograms is small but not riskfree (see section on radiation risk on page 36).

There isn't enough evidence to say whether the benefits of breast screening
outweigh the risks for younger women. We know that screening can reduce the
number of women who die from breast cancer, by finding cancers early. But
screening also sometimes finds cancers that would never otherwise have been
found or caused a woman harm. This is called overdiagnosis. As a result, some
women are diagnosed and treated for a cancer that would never otherwise have
been found. Researchers aren't sure whether screening younger women would
save enough lives to outweigh the risk of finding and treating cancer that may
never have caused harm. (Please see page 28 for information on the benefits
and risks of breast screening.)
In 2002, the World Health Organization's International Agency for Research on Cancer
reviewed the research on the most appropriate age group for women to have breast
screening. It found evidence that the benefits of screening outweighed the harms for
women aged 50 to 69.77 More recent reviews of studies in the US and Canada came to
similar conclusions. They found that the benefits of screening are more likely to
outweigh the harms for women aged 50 and older, than they are for women aged 40 to
49.78 79 Research on this subject continues, including the NHS Breast Screening
Programme Age Extension Trial which is investigating the benefits and risks of breast
screening in women aged 47 to 49 and 71 to 73.71
14
Why is breast screening offered every three years?
How frequently women should be offered breast screening is also a matter of debate.
Some countries encourage women to have a screening mammogram every year, or
every two years. In the UK, women are invited to have breast screening every three
years.
One large, high-quality study (a randomised controlled trial) in the UK looked at this
question. The study compared women screened every three years with women
screened every year. Based on the number of cancers detected over three years, the
researchers predicted the number of women who would die of breast cancer if they
were screened every year versus every three years. The researchers found that
screening women every year would have no significant effect on the risk of dying from
breast cancer compared to screening every three years.80
Women over age 70 (or over 73 if they are part of the age extension trial) do not receive
screening invitations from the NHS Breast Screening Programme. If they wish to, they
can continue to have screening mammograms every three years by making an
appointment with their local breast screening unit.
Screening for women with a family history of breast cancer
Some women are offered screening more often than every three years and from a
younger age than 50. This is because breast cancer runs in their family and these women
may have inherited genes that put them at higher risk of getting breast cancer. Cancer
that is due to inherited genes is called familial breast cancer or hereditary breast
cancer.
Having one or more relatives with breast cancer does not necessarily mean that breast
cancer runs in a woman's family. Most cancers happen by chance, with less than 10 in
100 thought to be related to inherited genes.30 But if a woman has more than one close
relative diagnosed with breast cancer, particularly if close relatives have developed
breast cancer at a young age or in both breasts, this could be a sign of inherited genes in
the family.
If a woman is concerned about familial breast cancer, she can talk to her GP, who may
refer her for an assessment based on her family history.
If a woman is found on assessment to have a raised or high risk of breast cancer, she
may be offered annual screening with a mammogram, a magnetic resonance imaging
(MRI) scan, or possibly both. Once the woman reaches age 50, she will usually stop
being offered annual screening and instead be invited to have three-yearly breast
screening as part of the NHS Breast Screening Programme.
Some women with a very high risk of breast cancer may continue to have more frequent
screening, for example for women whose family is known to carry an abnormal breast
cancer gene.81
15
Genetic counselling and testing
If a woman's family history suggests she is at high risk of developing breast cancer, she
will be offered a referral to a genetic counsellor. The counsellor will estimate the
woman's risk based on her family history and other risk factors.81
If the genetic counsellor finds that the woman has more than a 20 in 100 chance of
having a breast cancer gene in her family, the woman will be offered genetic testing.
Genetic testing looks for three types of faulty genes in a sample of blood: BRCA1,
BRCA2, and TP53. It's the woman's choice whether she has this testing. The genetic
counsellor will explain what the test involves and the possible results. He or she will also
answer any questions the woman might have. If a woman decides to have genetic
testing, the test must first be carried out on a relative who has had either breast cancer
or ovarian cancer. This provides the best chance of detecting a faulty gene. If a faulty
gene is found, then the woman and other members of her family have the test.
16
4. What happens at the breast screening appointment?
NHS Breast Screening uses an X-ray test called a mammogram to check the breast for
signs of cancer.
All mammograms are carried out by women. These women are sometimes called
mammographers and are specially trained to take mammograms. They could be either
radiographers (healthcare professionals specialised in taking X-rays) or assistant
practitioners (healthcare professionals specialised in taking X-rays who work under the
supervision of radiographers). When a woman arrives at a breast screening unit, the
staff there will check her details, ask about any previous breast problems, and answer
any questions.82
Having a mammogram
To have a mammogram, women need to undress to the waist. For this reason, they may
prefer to wear a skirt or trousers (rather than a dress) to their appointment. Before
taking the mammogram, the mammographer explains what is about to happen. She
then places the woman's breast onto the mammogram machine and lowers a plastic
plate onto the breast to compress it. This helps to keep the breast still and to get the
clearest X-ray possible, with the lowest dose of radiation.
Usually, two X-rays are taken of each breast (a so-called two-view mammogram) – one
from above (called cranio-caudal) and one from the side (called oblique). Research
shows that taking two X-rays increases the chance of detecting small cancers, compared
with taking only one.83 The mammographer goes behind a screen while the X-rays are
taken so that she is not exposed to unnecessary X-rays. The woman has to keep still for
several seconds each time.
The mammogram takes only a few minutes and the whole appointment usually takes
less than half an hour.
What does having a mammogram feel like?
Some women feel uncomfortable or embarrassed about removing their clothes for a
mammogram, or are anxious about the test and its possible results.84
Very little has been published in the scientific literature about how women feel about
the experience of having a mammogram. One UK study looked at the reasons why
women decide not to have screening again after their first mammogram. About 3 in 100
women said it was because they had felt embarrassed at their first appointment. About
6 in 100 said it was because screening was stressful for them. However, this study was
done in 1994. We can't be certain that it reflects how women might feel about
screening today.85
Having a mammogram can be physically uncomfortable because the breast is squeezed
between the two plastic plates on the mammogram machine. Some women say they
17
find it painful but others don’t. Usually, any pain from the mammogram passes quickly,
but some women have pain or soreness for a few days.86
We don't know for certain how many women experience pain when having a
mammogram because different studies show very different results.87 A systematic
review of research on breast screening in women aged 40 to 49 found that the number
of women who said they experienced pain during breast screening varied considerably
across 22 studies reviewed. The authors mention one study in which 77 in 100 women
found mammography painful compared to another in which 28 in 100 women said they
experienced considerable pain. The authors suggested that the wide range in the
prevalence of pain may be because of variations in how the studies defined and
measured pain, and how soon after having a mammogram women were asked about
pain.88
Some research suggests that if women are given detailed information about what to
expect before their mammogram, they feel less pain and discomfort.89
If women experience pain during breast screening, they should inform the
mammographer, who may be able to make them more comfortable.
Mammograms for special circumstances
Special arrangements may need to be made for some women to have breast screening.

Women who have a physical disability. Women should contact their breast
screening unit if they have a physical disability that might make it difficult for
them to have a mammogram (for example, if they cannot stand up or find
climbing steps difficult, because many mammograms are done in mobile vans).
The unit will advise them on whether a mammogram is technically possible, and
where it can be performed. For example, if a woman is unable to walk and uses a
wheelchair, she will probably be advised to have a mammogram at a hospitalbased unit, rather than at a mobile unit. A mammogram also requires some
upper-body mobility and strength, as the woman is carefully positioned on the
mammogram machine and must hold the position for several seconds at a time.
This may not be possible for women with limited upper-body mobility or who are
unable to support their upper body without assistance. If a woman is not
physically able to have a mammogram, she will continue to receive screening
invitations in case her mobility improves.90

Women who have breast implants. Women with breast implants can still have
mammograms. The pressure put on the breasts during the mammogram should
not damage or cause problems with the implants. Women with implants need to
attend a screening unit that has the ability to view mammogram images straight
away. This is to make sure the mammogram shows as much of the tissue around
the implant as possible. When a woman receives her screening invitation, she
should let her screening unit know about her implants to find out whether she
should attend a different location for her mammogram.91 If a woman has
18
implants because she previously had all her breast tissue removed through a
mastectomy, she does not need breast screening.

Women who are pregnant or breastfeeding. Most women who receive an
invitation for breast screening are past the menopause and cannot get pregnant.
If a woman is pregnant or breastfeeding when she receives an invitation, she
should contact her breast screening unit to see whether she should delay
screening.92

Women who have recently had a mammogram. Most women invited through
the Screening Programme will not have recently had a mammogram. If a woman
has, for example, because she had some breast symptoms and has been referred
to a specialist to check these, she should contact her local screening unit as she
may be advised to delay her next breast screening appointment.

Women who have a learning disability. The process of having a mammogram is
the same for women with a learning disability as for other women. However, the
potential benefits and risks of breast screening, and the mammogram process,
will need to be explained in terms that the woman can understand, so she can
make a decision about whether to participate. If a woman does not have the
mental ability to make her own decision about screening, her carer may make a
decision on her behalf. This is called a 'best interests' decision. It's the same as
the other care and treatment decisions that a carer might make for someone
unable to make their own decisions. If a woman's mental ability improves from
time to time, the decision about screening should be delayed until she can make
a decision for herself.90 92
What happens to a woman’s mammogram after screening?
The NHS Breast Screening Programme keeps a woman’s mammograms for at least eight
years. These are saved securely. The Screening Programme regularly checks records to
make sure the service is as good as possible. Staff in other parts of the health service
may need to see a woman’s screening records for this, including her previous
mammograms. These records are only shared with people who need to see them.
If a woman would like more information or would like to know the results of these
regular checks she can contact her local screening unit.
19
Figure 2: A woman having a mammogram with a mammographer
20
5. What are the possible results of breast screening?
The mammograms are checked by a team of health professionals trained in reading
mammograms. Within two weeks of her appointment, the woman will receive a letter
with her breast screening results. The results will also be sent to her GP. Most women
have a normal result from breast screening, while some women need more tests. 13
Most women will have a normal result
Most women (about 96 in 100) have a normal result,13 which means their mammogram
shows no signs of breast cancer. This may also be called a ‘negative’ mammography
result.
A woman who has a normal result will continue to receive invitations for breast
screening every three years until she reaches 70 years of age, or 73 if she is part of the
age extension trial (see page 13). Once a woman is over the age of 70 (or 73) she will no
longer automatically receive invitations from the NHS Breast Screening Programme. She
can still have breast screening every three years but will need to ask her local breast
screening unit for an appointment. It is important to remember that a woman should
see her GP straight away if she notices any changes in her breasts, because cancer can
develop between breast screening appointments (please see page 8 for more
information on the symptoms of breast cancer).
Some women will need more tests because they have an
abnormal result
Some women (about 4 in 100) may receive a results letter saying they need more
tests.13 Professionals sometimes call this an ‘abnormal’ or a ‘positive' mammography
result, because something has been found which does not look normal. This does not
mean the tests will find cancer.
21
Figure 3: Outcomes for 100 women attending breast screening at a given time.
22
What happens if a woman as an abnormal result?
If a woman has an abnormal result, she will be invited for an appointment at a breast
assessment clinic to have more tests. Breast assessment clinics are usually in hospitals.
Of the 4 in 100 women who need more tests because of an abnormal result, about 3 will
find out they do not have cancer and 1 will find out she does. 13
Tests at the breast assessment clinic can include clinical examination, imaging
(mammograms or ultrasound), and tissue sampling (needle aspiration or biopsy). This is
sometimes called triple assessment because it involves three types of assessment. Not
all women will need all of these tests.
Clinical examination: A doctor or a nurse practitioner carefully examines and feels the
woman’s breast tissue as well as the lymph nodes under her arms and in her neck.
Mammogram: Additional mammograms may be done at different angles or with
magnification to get more detailed X-ray images of the breast tissue.
Ultrasound: An ultrasound uses sound waves to make images of the inside of the
breast. This test can sometimes show whether a lump is solid or whether it's a cyst filled
with fluid. During an ultrasound, a specialist puts gel on the woman's breast and rubs a
small probe over the breast. Images of the breast tissue show up on a screen.
Fine needle aspiration: A doctor uses a fine needle and syringe to collect some cells
from a woman's breast. The sample is sent to a laboratory where it is examined for signs
of cancer.
Core needle biopsy: A doctor uses a bigger needle than in fine needle aspiration to
collect a small sample of tissue (a biopsy) from the breast. The woman will be given an
injection to numb the area so she won't feel pain (a local anaesthetic). The sample
removed during the biopsy is sent to a laboratory where it is examined for signs of
cancer.
Core needle biopsies are now more common than fine needle aspirations. Both tests
work, but it's easier for the doctor to get enough cells to test with a core biopsy.93-95
This means that the woman is less likely to need a second test to collect more cells. In
both tests, the doctor may guide the needle by feeling the lump in the woman's breast.
If it's not easy to feel the lump, the doctor might use an ultrasound or mammogram to
guide the needle to the right place.
Occasionally, a woman will have an open biopsy. This involves having an operation to
remove one or more tissue samples through a small cut in the breast. The woman is
usually given a general anaesthetic, so she won't be awake during the operation. Fewer
than 3 in 100 women invited for more tests need an open biopsy.96
The waiting time for the test results varies. Some women will find out their results the
same day as their test, or a few days later. If a sample needs to be sent to a laboratory,
the waiting time can be longer. Women can usually expect their results within one week
but can ask at their breast assessment clinic when to expect their results.
23
However long a woman has to wait, this will be an anxious time. If she wants someone
to talk to, her breast assessment clinic may be able to put her in touch with a health
professional who may be able to help.
Some women will need another mammogram before they get
their result
Occasionally, a woman will receive a letter saying there was a technical problem with
her mammogram. This usually means that the X-rays were not clear enough to read.
Before she can get her result, she will be called back for another mammogram to get
clearer X-rays.
24
6. What happens if the tests show breast cancer?
For every 100 women aged 50-70 who have a mammogram, about 1 of them will be
diagnosed with breast cancer.13
Non-invasive breast cancer
Out of 100 women diagnosed with breast cancer through screening, about 20 will have
non-invasive breast cancer.13 This means there are cancer cells in the breast, but they
are only found inside the milk ducts (tubes) and have not spread into surrounding breast
tissue. This is also called ‘ductal carcinoma in situ’ (DCIS). In some women with noninvasive breast cancer, the cancer cells stay inside the ducts and may never cause harm.
In other women, the cancer cells will grow into (invade) the surrounding breast tissue in
the future.
When a woman is diagnosed with non-invasive breast cancer, doctors can’t tell whether
it will grow into the surrounding breast or not.
Invasive breast cancer
Out of 100 women diagnosed with breast cancer through screening, about 80 will have
invasive breast cancer. 13 This is cancer that has grown out of the milk ducts and into the
surrounding breast. Most invasive breast cancers will spread to other parts of the body if left
untreated. But in some cases, an invasive breast cancer can grow so slowly that it would
never cause a woman harm in her lifetime.
Figure 4: The difference between a normal milk duct, non-invasive breast cancer and
invasive breast cancer
25
7. Treatment for women diagnosed with invasive and
non-invasive breast cancer
All women diagnosed with invasive and non-invasive breast cancers are offered
treatment. A woman found to have breast cancer will have the care and support of a
team of breast cancer specialists. The team will explain the type of cancer found,
answer questions, and discuss the woman’s treatment options with her.
Nearly all women diagnosed with breast cancer through screening will have surgery to
remove their cancer and to reduce the risk of the cancer returning. Women may be
offered either mastectomy or breast-conserving surgery (usually
called lumpectomy or wide local excision). In a mastectomy, the entire breast with
cancer is removed, and some lymph nodes or small muscles near the breast may also be
removed. In breast-conserving surgery, only the area where the cancer is growing in the
breast is removed. Women may also have other treatments to reduce the risk of their
cancer returning. These can include:
Radiotherapy: This treatment directs radiation at the breast and possibly the lymph
nodes to kill any cancer cells that might have been left behind after surgery.
Chemotherapy: Chemotherapy drugs are used to kill any cancer cells left in the breast,
lymph nodes, and other parts of the body.
Hormonal therapy: The growth of some breast cancers is promoted by the hormone
oestrogen. Hormonal therapy reduces the amount of oestrogen in the body or blocks
the effects of oestrogen. This helps stop the cancer growing or spreading, and can stop
the cancer coming back after surgery. Some women take medicines (tamoxifen,
goserelin (Zoladex), anastrozole, exemestane or letrozole). Others have radiotherapy to
stop their ovaries making oestrogen, or have surgery to remove their ovaries. 97
Biological therapy: Biological therapy can change the way cancer cells behave to make
them stop dividing and growing. It can also kill any cancer cells and encourage the
body’s immune system to attack them.98 Each woman’s cancer cells are tested to see if
biological therapy (for instance, trastuzumab (also known as Herceptin) or lapatinib
(also known as Tyverb)) may be effective.
What treatment a woman is offered will depend on several things, including:







The size of her cancer
Where the cancer is in her breast
What type of breast cancer she has
Whether the cancer cells are likely to respond to biological therapy
Whether it has spread to other areas and, if so, where it has spread
Her general health
The potential benefit of each treatment weighed against its potential harms.
If a woman is diagnosed with breast cancer, a breast cancer specialist will discuss the
treatment options available with her, and answer any questions. Together they will
decide on the best treatment approach.
26
8. How good is breast screening at finding cancer?
Research shows that when women have the type of mammography used in the NHS
Breast Screening Programme, breast screening finds most breast cancers. Rarely, it
misses a cancer. Also some cancers might grow in between screening appointments.
Cancers that grow and are diagnosed between screening appointments are called
Interval cancers.
One study in Norway found that about 17 women in every 10,000 who received a
normal screening result developed breast cancer in the two years before their next
screen. It is not possible to tell whether the interval cancers diagnosed were present
but too small to detect at breast screening or whether they only started to develop after
the woman’s last breast screening appointment and grew more quickly.
On rare occasions, a breast cancer may be visible on a screening mammogram but is
missed by the team checking the mammogram for cancer. If a woman is diagnosed with
breast cancer between screening appointments and her most recent breast screening
result was normal, the mammogram will be checked again to see if there was an
abnormality that should have been spotted. Breast cancer is missed in between 2 and 4
in every 10,000 women aged 50 to 70 who attend for breast screening every three
years.99
Because of the possibility of breast cancers being missed or growing in between
screening appointments, it is important for women to get to know how their breasts
normally look and feel. They should know about the symptoms of breast cancer and see
their GP straight away if they notice any changes to their breasts (please see page 8 for
more information about the symptoms of breast cancer).
27
9. Weighing up the possible benefits and risks of breast
screening
The main benefit of breast screening is that it saves lives from breast cancer. This is
because cancers are diagnosed and treated earlier than they would have been without
screening.
The main risk of breast screening is that it can find cancers that would never otherwise
have been found and would not have become life-threatening. Doctors cannot always
tell whether a breast cancer that is diagnosed will go on to become life-threatening or
not, so they offer treatment to all women diagnosed with breast cancer. This means
that some women will be offered treatment that they do not need.
Screening saves lives from breast cancer
Women who attend breast screening have a lower chance of dying from breast cancer
than women who do not attend.
An independent UK panel of experts reviewed the evidence on the benefits and risks of
breast screening in 2012 and estimated that99:

For every 200 women screened every three years between the ages of 50 and
70, about 3 women will die of breast cancer by the time they are 80.

For every 200 women not screened every three years between the ages of 50
and 70, about 4 women will die of breast cancer by the time they are 80.
So, about 1 less woman dies from breast cancer for every 200 women who attend
breast screening every three years between the ages of 50 and 70. This adds up to
about 1,300 lives saved every year from breast cancer in the UK. There is debate among
doctors and scientists about how effective breast screening is at reducing breast cancer
deaths. The numbers given here are the current best estimate of the benefits of breast
screening. The figures come from combining the results of 11 large high quality studies
(randomised controlled trials) that looked at what happened to women who were
randomly selected either to be invited for screening, or not to be invited for screening.
However, these studies have some limitations. Most were carried out at least 20 years
ago, and treatment for breast cancer has improved since then. Techniques for detecting
breast cancer have also improved. The results vary a lot between the studies, because
the studies looked at women of different ages, and over different periods of time.
Although we know that screening saves lives from breast cancer, we do not know
whether breast screening reduces the overall numbers of deaths among women
screened every three years between the ages of 50 and 70. Women who would
otherwise have died of breast cancer may die of other causes instead. So we can't say
that breast screening reduces deaths overall, only that it reduces deaths from breast
cancer.
28
Breast screening finds breast cancer that would never have
caused harm to a woman
The main risk of breast screening is that some women will be diagnosed with breast
cancer that would never otherwise have been found and would not have become lifethreatening. This is known as overdiagnosis. Breast cancer only becomes lifethreatening when it grows and spreads to other parts of the body, and some breast
cancers that show up on a mammogram are either growing very slowly or not growing
at all. Some women can live their entire life with an invasive or non-invasive breast
cancer that never causes them harm. These women would never need treatment for
their breast cancer, unless it is found through screening. Overdiagnosed breast cancers
are not wrong diagnoses – they are genuine breast cancers.
When breast cancer is found through screening, doctors cannot always be certain about
whether it will grow and become life-threatening or not. So they offer treatment to all
women found to have breast cancer. This means that some women are offered
treatment that they do not need.
Nearly all women who have a cancer found through screening have surgery to remove
all or part of the breast.13 Some will have other treatments too, such as radiotherapy to
the breast, and hormone therapy or chemotherapy treatments. These treatments can
have serious side effects.
Unfortunately, there is no way of knowing whether or not a treatment was necessary,
or which women were overdiagnosed. There is uncertainty among doctors and scientists
about how many women are overdiagnosed with breast cancer. The numbers we give
here are a best estimate from the Independent UK Breast Screening Review which
estimated that99:

about 15 out of every 200 women who are screened every three years between
the ages of 50 and 70 will be diagnosed with breast cancer.

about 3 of these women will be diagnosed and treated for a breast cancer that
would never have become life-threatening, in other words an overdiagnosed
breast cancer.
The independent UK review estimated that about 19% of breast cancers diagnosed in
women invited for screening aged 50-70, are overdiagnosed. This means that every year
about 4,000 women in the UK are diagnosed and treated for breast cancer that would
never have become life-threatening.
However, because of the limitations of the studies, uncertainty around this estimate is
very great. Scientists have estimated that it could be anything between 0% (no breast
cancers are overdiagnosed) and 50% (half of all screening-detected breast cancers are
overdiagnosed).
29
Figures 5 and 6 both show the benefits and risks of breast screening, as estimated by
the Independent UK Review of Breast Screening. 99 100 Figure 5 shows what would
happen to 200 women who choose to have breast screening every three years, when
invited as part of the NHS Breast Screening Programme. As such, it shows the benefits
and risks of having breast screening. Figure 6 shows what would happen to 200 women
who choose to have breast screening and 200 women who choose not to have breast
screening. In this way, the benefits and risks of both having breast screening and not
having breast screening can be weighed up against each other. Different people prefer
and understand different ways of representing information. This is why we have chosen
to present the benefits and risks of screening in two different ways in these diagrams.
30
Figure 5: Benefits and risks of breast screening, as estimated by the Independent UK Review of Breast
Screening
31
Figure 6: Benefits and risks of breast screening as estimated by the Independent UK Review of Breast Screening (alternative version)
32
How can we tell that some women are diagnosed with cancer
that would never have caused them harm?
Breast screening increases the number of women who are diagnosed with breast cancer
between the ages of 50 and 70, because it finds breast cancers that are usually too small
to see or feel and that would not therefore have caused symptoms until later on. So you
might expect that by the age of 80 the numbers of women with breast cancer would be
the same as if there was no screening. However, the evidence shows that some of the
cancers diagnosed through screening would never have been diagnosed if screening had
not been done.99
Before women were offered breast screening, non-invasive cancers were not often
detected, as they don't usually cause symptoms. Since the start of the NHS Breast
Screening Programme in 1988, the number of non-invasive cancers diagnosed has risen
dramatically. But these cancers are still not well understood. We know that most
invasive cancers are non-invasive when they first start. But not all non-invasive cancers
become invasive. Some will never spread, or they will grow so slowly that they would
have never caused a woman harm in her lifetime. Non-invasive breast cancers only
account for some of the cancers diagnosed through screening that would never
otherwise have been diagnosed. Research suggests that some invasive cancers
diagnosed through screening might never otherwise have been found or caused a
woman harm.101 In some cases, it might be that the cancer would never put the
woman's life at risk, because she would die of something else before it started to cause
problems.
There is no way for a woman or her doctors to know for certain whether or not a breast
cancer that is diagnosed through screening would have ever become life-threatening.
Almost all women diagnosed with cancer have surgery to remove their cancer, including
99 in every 100 women diagnosed with non-invasive cancer.13
For some women, this early detection and treatment will be lifesaving. But for others, it
will mean having potentially harmful treatments that they don't need. They will also
have unnecessary stress and anxiety about a cancer they would never have found out
about if they hadn't had screening.
Researchers are trying to find better ways of telling which women have breast cancers
that will be life-threatening and which women have cancers that will not.
33
What is the balance of the main benefits and risks of breast
screening?
On average, for every 1 woman who has her life saved from breast cancer through
breast screening, 3 women are diagnosed and treated for a breast cancer that would
never otherwise have been found or caused a woman harm in her lifetime.
Figure 7: Weighing up the main benefit and risk of breast screening
34
Other benefits of breast screening
Reassurance from a normal result
A normal breast screening result can be reassuring.84 102 It is important to remember
that it is still possible to develop breast cancer after a normal breast screening result. It
is, therefore, useful for women to know how their breasts normally look and feel so that
they can detect any changes. Women should make an appointment to see their GP
straightaway if they experience any symptoms of breast cancer. (Please see page 8 for
more information about the symptoms of breast cancer.)
Chance of having a mastectomy
It has been suggested that breast screening might make women with breast cancer less
likely to have a mastectomy, because cancers found by screening tend to be at an
earlier stage, when breast-conserving surgery, for example, removal of the lump only
(lumpectomy), is more likely to be possible.
However, studies of whether breast screening decreases or increases rates of having a
mastectomy rather than breast-conserving surgery do not provide a definitive
answer.103-106 Other factors such as surgeon and patient preference have an important
influence on rates of breast-conserving surgery and mastectomy.107-110
When offered the choice about whether to have breast-conserving surgery or
mastectomy, women’s preferences vary.107-109 Some women may prefer to have their
entire breast removed, while others may prefer breast-conserving surgery.
It is important that the team of specialists providing care for a woman diagnosed with
breast cancer provide her with accurate information about the benefits and risk of the
treatments so she can make an informed decision.
Other risks
Psychological effects of abnormal results
Having an abnormal result on a mammogram (which some professionals call a positive
result) does not mean a woman definitely has cancer. For 80 in 100 women who have an
abnormal result, further tests show they do not have cancer. These women are said to
have had a false positive result. This can be worrying for women even if they turn out
not to have cancer, and some may feel distress which affects their ability to do their
normal day-to-day activities at the time.111-116
The evidence on how much distress a false positive result can cause is not clear. Two
large studies of over 700 women have found that six weeks later there was no
difference in levels of poor mental health between women who had a false positive
result and those who had a normal result six weeks after the mammogram.113 117
Another, smaller study suggests that women who have had a false positive result may
35
have more psychological problems after three years than women who had normal
results115 116 118: in 99 women with a normal result, 25% had a score of 12+ on the
Psychological Consequences Questionnaire; in 280 women with false positives, 63% had
a score of 12+ (possible range of scores 0-36). Women with a score of 12+ would have
said they experienced varying degrees of a range of negative thoughts and behaviours.
These may have included a change in appetite, feeling worried, nervous or panicky,
trouble sleeping, feeling depressed or feeling withdrawn. Having psychological problems
is more likely when women have a tissue or cell sample taken from their breast (a
biopsy).118
False reassurance from a normal result
Very rarely, breast screening can miss a cancer. It is also possible for breast cancer to
develop between a woman’s three-yearly screening appointments (this is called an
Interval cancer). The potential risk is that after a normal screening result, a woman
might be reassured, and so ignore any symptoms of breast cancer she experiences. She
might delay reporting her symptoms because she thinks her recent normal result shows
there is nothing to worry about. This could delay diagnosis and treatment of her cancer.
For this reason, it is important for women to look out for the symptoms of breast cancer
and to get to know how their breasts normally look and feel. They should make an
appointment to see their GP straightaway if they experience any breast cancer
symptoms, even if their most recent mammogram was normal.
Radiation exposure
Mammograms are X-rays, which means they use a small amount of radiation to create a
picture of the breast. Having many X-rays increases a woman's exposure to radiation.
Rarely, X-rays can cause cancer. Among women who have screening every 3 years from
age 47 to 73, about 3 to 6 in every 10,000 may develop cancer due to X-rays from
screening.119
36
10. Sources of more information about breast screening
Women should contact their local breast screening unit with any questions about NHS
Breast Screening. If they would like to talk to someone about whether to have breast
screening, their GP will be able to help. Together, they can weigh up the possible
benefits and risks, to help the woman decide.
More detailed information on breast screening can be found on:
The NHS Breast Screening Programme website:
www.cancerscreening.nhs.uk/breastscreen
The Informed Choice about Cancer Screening website:
www.informedchoiceaboutcancerscreening.org
The following charity websites may also provide helpful information about breast
screening:
Cancer Research UK
www.cruk.org
Healthtalkonline
www.healthtalkonline.org
Breakthrough Breast Cancer
www.breakthrough.org.uk
Breast Cancer Campaign
www.breastcancercampaign.org
Breast Cancer Care
www.breastcancercare.org.uk
37
Acknowledgments
We would like to acknowledge the contributions of the British Medical Journal Evidence
Centre and Best Health. They were involved in reviewing the evidence necessary to
write this document. They also contributed to the early stages of writing. We would also
like to acknowledge Professor David Spiegelhalter for his contributions to the
development of the diagrams (icon arrays) showing the benefits and risks of breast
screening, as estimated by the Independent UK Review of Breast Screening.
38
Glossary
Advanced breast cancer: Also referred to as stage 4 breast cancer, advanced invasive
breast cancer or metastatic cancer. This usually means the cancer has spread to other
parts of the body. It can also mean that the cancer hasn't spread but has grown directly
into tissues close to the breast and cannot be removed through surgery.
Benefit: A benefit is a good outcome. In the case of breast screening, the main benefit is
lives saved from breast cancers. The opposite of a benefit is a harm (a bad outcome).
We refer to the possible harms of breast screening as ‘risks’ in this evidence resource.
Biological therapy: A way of treating breast cancer and trying to stop it coming back.
Biological therapy can change the way cancer cells behave to make them stop dividing
and growing. It can also kill any cancer cells and encourage the body’s immune system
to attack them.
Biopsy: A procedure in which a tiny sample of tissue is taken from the body (in this
case, the breast) to examine more closely under a microscope. Core needle biopsy, fine
needle aspiration and open biopsy are three ways in which a biopsy is taken following
an abnormal breast screening result.
Breast assessment clinic: Clinics that are usually based in hospitals where further tests
after an abnormal mammography result are carried out.
Breast-conserving surgery: Surgery used to treat breast cancer in which only the area of
the breast with the cancer, and a small amount of healthy breast tissue around it, is
removed. This is usually called a lumpectomy or a wide local excision. A less common
type of breast-conserving surgery is quadrantectomy in which about a quarter of the
breast is removed.
Chemotherapy: A way of treating breast cancer and trying to stop it coming back.
Chemotherapy drugs are used to kill any cancer cells left in the breast, lymph nodes, and
other parts of the body.
Clinical examination: This is when a doctor or a nurse practitioner carefully examines
and feels the woman’s breast tissue as well as the lymph nodes under her arms and in
her neck.
Core needle biopsy: This is used as a follow-up procedure after an abnormal breast
screening result. A doctor uses a bigger needle than in fine needle aspiration to collect a
small sample of tissue (a biopsy) from the breast. A local anaesthetic is given to numb
the area. The sample removed during the biopsy is sent to a laboratory where it is
examined for signs of cancer.
Ductal breast cancer: Cancer that starts in the ducts of the breasts. It is the most
common type of breast cancer.
39
Ductal carcinoma in situ: Also known as non-invasive breast cancer. This is when there
are cancer cells in the breast but they are only found within the milk ducts and have not
spread any further.
Early invasive breast cancer: Also referred to as stage 1 breast cancer. It has grown out
of the ducts or lobules into the surrounding breast tissue. The tumour, if present, is
small (2 centimetres or less across) and the cancer has not spread to the lymph nodes,
or only very few cancer cells are in the lymph nodes.
False positive: A false positive occurs when someone tests positive for a certain medical
condition but in fact does not have the medical condition. In breast screening, a false
positive occurs when a woman receives an abnormal (positive) mammography result,
but then goes for further tests and finds out that she does not have breast cancer. This
might also be called a false alarm.
Familial breast cancer: Breast cancer that is due to inherited genes, also called
hereditary breast cancer.
Fine needle aspiration: This is used as a follow-up procedure after an abnormal breast
screening result. A doctor uses a fine needle and syringe to collect some cells from a
woman's breast. The sample is sent to a laboratory where it is examined for signs of
cancer.
Grade: This is a way used by breast cancer specialists to describe how different the
cancer cells look from normal breast cells when they are looked at under a microscope.
Grades are usually described as 'low grade', 'intermediate grade', or 'high grade'.
Genetic counsellor: A genetic counsellor is a health professional who is specialised in
medical genetics and counselling.
Genetic testing: Genetic testing is offered to women with a higher than 20 in 100
chance of having a breast cancer gene in their family. Genetic testing looks for three
types of faulty genes in a sample of blood: BRCA1, BRCA2, and TP53. Genetic testing
must first be carried out on a relative who has had either breast cancer or ovarian
cancer. This provides the best chance of detecting a faulty gene. If a faulty gene is
found, then the women and other members of their family have the test.
Harm: A harm is a bad outcome. In the case of breast screening, the main harm is that
of being diagnosed and treated for a cancer that would never otherwise have been
found or caused harm. In this evidence resource and in the leaflet about NHS breast
screening, we refer to the possible harms of breast screening as risks. We chose to use
‘risk’ rather than the word ‘harm’ because members of the public who contributed to
the development of the NHS breast screening information found the work ‘risk’ more
useful and less alarming: they felt that ‘harm’ implied something inflicted on purpose.
Hereditary breast cancer: Breast cancer that is due to inherited genes, also called
familial breast cancer.
Hormonal therapy: A way of treating breast cancer and trying to stop it recurring.
Hormonal therapy reduces the amount of oestrogen in the body or blocks the effects of
40
oestrogen to help stop breast cancer growing or spreading. It can also help stop cancer
coming back after surgery. It involves taking medicines, for instance tamoxifen,
anastrozole, exemestane or letrozole, or having treatment or surgery to stop the ovaries
making oestrogen.
Inflammatory breast cancer: A less common breast cancer that blocks the lymph vessels
in the skin of the breast. This makes the skin look pitted or dimpled, like orange peel.
The skin may also feel warm and often looks red. Some women with this kind of breast
cancer will develop an obvious lump in the breast but others will not. This type of cancer
can develop and spread quickly.
Interval cancer: An interval cancer is one that develops between screening
appointments. This does not mean the cancer was missed at screening. It means that it
started to grow and cause problems in the interval between screening appointments.
Invasive breast cancer: This is when the cancer cells have spread out of the milk ducts
and into the surrounding breast.
Lobular breast cancer: Cancer that starts in the lobules of the breast (parts of the
breast where milk is made). This is the second most common type of breast cancer.
Lobular carcinoma in situ: Is when some of the cells in the lobules of the breast are
abnormal. Although described as stage 0 breast cancer, it is not usually thought of as
cancer, because it is not life threatening and has not spread out of the lobules of the
breast. However, women with lobular carcinoma in situ have an increased risk of
eventually getting cancer in either breast.
Locally advanced breast cancer: Also referred to as stage 2 or 3 breast cancer. This
means the cancer is in a large part of the breast and may also be in the lymph nodes.
However, it hasn't spread to other parts of the body.
Lumpectomy: Breast-conserving surgery to treat breast cancer in which only the area of
the breast with the cancer, and a small amount of healthy breast tissue around it, is
removed. Also called a wide local excision.
Mammogram: An X-ray image of the breast.
Mammographer: Woman (usually a radiographer or assistant practitioner) specially
trained in taking mammograms.
Mastectomy: Surgery to treat breast cancer in which the entire breast with cancer is
removed. Some lymph nodes or small muscles near the breast may also be removed.
Metastasis (metastatic breast cancer): This is when a cancer spreads to other parts of
the body and becomes life-threatening.
Non-invasive breast cancer: Also known as ductal carcinoma in situ (DCIS). This is when
there are cancer cells in the breast but they are only found within the milk ducts and
have not spread any further.
41
Overdiagnosis: The main risk of breast screening. It happens when breast screening
finds cancers that would never otherwise have been found or caused a woman harm in
her lifetime.
Open biopsy: This is a follow-up procedure occasionally used after an abnormal breast
screening result. It involves having an operation to remove one or more tissue samples
through a small cut in the breast. A general anaesthetic is usually offered.
Paget’s disease of the breast: A less common breast cancer that affects the skin on and
around the nipple. Signs of Paget's disease can include itching, redness, and flaking of
the skin. In its early stages, Paget's disease is often confused with eczema and other skin
conditions. Women with Paget's disease often have cancer within their breast as well.
Quadrantectomy: Breast-conserving surgery to treat breast cancer in which about a
quarter of the breast is removed.
Radiotherapy: A way of treating cancer and stopping it recurring. To treat breast cancer,
radiation is directed at the breast and possibly the lymph nodes to kill any cancer cells
that might have been left behind after surgery.
Randomised controlled trial: Randomised controlled trials are considered the gold
standard in scientific research for evaluating health care. In a randomised controlled
trial, participants are randomly assigned to either receive an intervention or not (for
example to have breast screening or not). The researchers can then look at differences
in outcomes among the people who received the intervention and those who did not.
Risk: A risk is a chance of something occurring. This may be a good or a bad thing. In this
document and in the NHS breast screening leaflet, the term ‘risk’ is also used to describe
the possible harms of breast screening. The main risk of breast screening is of being
diagnosed and treated for a cancer that would never otherwise have been found or
caused harm. The word ‘risk’ was chosen rather than ‘harm’ because members of the
public who contributed to the development of the information found the work ‘risk’
more useful and less alarming. To them, ‘harm’ implied something inflicted on purpose.
Stage: This is how cancer specialists describe how advanced a cancer is. Breast cancers
are usually described as stage 0 to 4 (with stage 4 being the most advanced cancer).
Symptom: Something that is felt by a person and indicates that a disease might be
present. Symptoms are sensed by the person and are not necessarily apparent to other
people (for instance, pain or a lump or thickening in the breast).
Systematic review: A systematic review provides a thorough summary of all of the
relevant literature on a given research question and follows methods which make the
conclusions less likely to be biased. The findings of systematic reviews of randomised
controlled trials are considered to be very high quality scientific evidence.
Ultrasound: An ultrasound uses sound waves to make images of the inside of the breast.
This test is used as a follow-up test after an abnormal screening result. It can sometimes
show whether a lump is solid or whether it is a cyst filled with fluid. During an
42
ultrasound, a specialist puts gel on the woman's breast and rubs a small probe over the
breast. Images of the breast tissue show up on a screen.
Wide local excision: Breast-conserving surgery to treat breast cancer in which only the
area of the breast with the cancer, and a small amount of healthy breast tissue around
it, is removed. Also called a lumpectomy.
43
Notes on methods used to compile this evidence
resource
Two systematic searches were conducted. The first search was designed to identify
relevant papers providing background information on breast screening. It was run once
in Embase and Ovid MEDLINE and included relevant articles published between 2000
and 2012. The British Medical Journal and NHS Cancer Screening Programmes websites
were also searched for relevant articles published between 2007 and 2012.
The second search was designed to identify systematic reviews, randomised controlled
trials and observational studies on specific effects of breast cancer screening. It was run
in Ovid MEDLINE, Embase and the Cochrane Library and included studies published
between 1992 and September 2012.
Studies were selected for the evidence resource if the type of breast screening used was
a close match for the type used in the NHS Breast Screening Programme. UK-based
papers were prioritised in the selection process.
Data on estimates of overdiagnosis, mortality, and the probability of different screening
outcomes were drawn from the report of the Independent UK Review of Breast
Screening.99 100
44
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