Our breast screening guide explains the potential benefits and risks of routine NHS breast screening.

Women over 50 are invited for breast screening every three years to help spot breast cancers sooner. Breast screening can prevent women dying from breast cancer.

Breast Cancer Now encourages all women to attend. However, there are some risks to breast screening and we think you should know about these before making your decision. 

Getting an invitation to breast screening can raise many questions for women. Explore our guide to get the answers.

As you get older, your risk of breast cancer increases. Women aged 50 to 70 years are invited for NHS breast screening every three years to help spot breast cancers sooner. Women over 70 can still attend breast screening and can make their own appointment at their local screening unit or by asking their GP to refer them.

As part of a research trial, women aged 47 to 50 and 70 to 73 in some areas of England are being invited for breast screening too.

NHS breast screening prevents three or four women dying of breast cancer each day in the UK.

Hear Eluned Hughes, our Head of Public Health and Information, explain why the NHS offers breast screening:

A visit to a screening centre usually takes less than 30 minutes. Read through the steps of an appointment for more information.

1. Your appointment will be at a breast screening unit

This may be in a building or in a mobile unit (van). When you arrive, introduce yourself to the receptionist and wait for your appointment. You might be asked to complete a form.

 

2. All mammographers (radiographers or assistant practitioners) are women.

Your mammographer will introduce herself and ask you about any previous breast problems. She will explain how the mammogram is taken and answer your questions.


3. You will be asked to remove your clothing from the waist up.

The mammographer will place one of your breasts on the mammogram machine and take an image of your breast. She will then repeat the process at a different angle. This involves your breast being squeezed between two plates so that the image is clear and uses the minimum amount of X-rays. She will then repeat the process with your other breast. The process can be uncomfortable and some women find it painful, but this usually passes quickly.


4. Your mammographer will let you know when to expect your results.

This is usually by post within two weeks. She may also talk to you about checking your breasts regularly.


 

Hear three women's experiences of screening:

For every 100 women who have a mammogram taken…

  • 96 get a normal result (no sign of cancer)
  • 4 are asked to have extra tests

The results women may get

For every 100 women who have a mammogram test, about 96 get a letter saying they have had a normal result. This means there is no sign of breast cancer and they will next be asked to go for screening in three years’ time. As a breast cancer could develop before their next mammogram, it is still important that they check their breasts regularly themselves too, and visit their doctor if they notice anything unusual.

The other four women will be asked to have extra tests at a specialist breast unit or centre. This is because the radiologists (or other qualified specialists) who read the mammogram images have spotted an area that looks different from the surrounding tissue. This is most common after your first mammogram, because the screening service does not yet know what looks normal for you.

Being called for extra tests does not necessarily mean you have cancer. In fact, about three out of every four women who have extra tests are told they don’t have breast cancer. For the woman who does have breast cancer, early diagnosis means she might begin treatment sooner and have the best chance of her cancer being treated successfully.

Although mammograms usually produce good images first time, occasionally a technical error can stop the image coming out clearly. In these instances, women get a letter asking them to return to the unit to have their mammogram repeated. With new technology, it is thought this will happen less often. New digital technology can allow your mammographer to check the image immediately. They may ask to repeat the process straightaway if they can see the image isn’t good enough, saving you a later trip back to the centre.

Macmillan breast care nurse Lorraine Walker explains what happens if you need extra tests:

What breast cancer treatment involves

If you are diagnosed with breast cancer, you will have a team looking after you, including specialist doctors and nurses, who will explain the best treatment options for you. This will take into account the type of breast cancer you have, how likely it is to grow and spread, and your preferences.

They will explain each stage of your care and help you to make decisions about your treatment.

  • This will usually involve surgery to remove the tumour
  • Some women also have radiotherapy – which is treatment with radiation to kill any remaining cancer cells
  • You may also need some form of drug treatment

Treatments work well for most women, removing the cancer and stopping it from spreading. They also reduce the chance that the cancer will come back. For example, research has shown that radiotherapy can halve the risk of the cancer returning. Your breast care team will be there to guide you through your treatment. Learn more about how breast cancer is treated in our treatment section.

For every 200 women screened every three years from ages 50 to 70 one fewer woman dies of breast cancer (compared with 200 women not screened).

Watch our video on how screening can prevent women dying from breast cancer:

See numbers on how screening can prevent women dying from breast cancer:

Imagine two groups of 200 women aged 50 to 70: Of the 200 women not screened, 188 will not be diagnosed with breast cancer; 12 will be diagnosed with breast cancer; eight will be treated and survive; and four will be treated by die. Of the 200 women screened, 185 will not be diagnosed with breast cancer; 15 will be diagnosed with breast cancer; 12 will be treated and survive; and 3 will be treated but die. That's one more death prevented for every 200 women who attend breast screening from age 50 to 70.

The numbers given are based on estimates made by experts using the best data available and have been rounded up for simplicity.

One in five women whose breast cancer is picked up by breast screening will receive treatment but their cancer might not have caused problems. This is called over-treatment.

Professor Malcolm Reed, Dean and Professor of Surgical Oncology, Brighton and Sussex Medical School, explains why over-treatment happens:

The additional risks of screening

As well as over-treatment, there are two more risks of breast screening that you should know about:

Occasionally, screening can miss breast cancer

Occasionally, a mammogram can miss a sign of breast cancer. Breast cancers can also develop between breast screening appointments. That’s why it’s important to check your breasts regularly and speak to your doctor if you notice anything unusual, even if you get a normal mammogram result.

Very rarely, mammogram X-rays can cause breast cancer

The X-rays used to take mammograms can, on very rare occasions, trigger a cancer to develop. Women who attend routine breast screening every three years for 20 years, have a slightly increased risk of developing cancer at some point in their life. Risks are kept as low as possible by compressing the breast when the mammogram is taken, which gives the best image possible with the lowest amount of X-rays.

How many women going for breast screening are over-treated?

The numbers of women over-treated:

Imagine two groups of 200 women aged 50 to 70: Of the 200 women not screened, 188 will not be diagnosed with breast cancer; 12 will be diagnosed with breast cancer; 0 will be treated but their breast cancer would not have caused a problem anyway (over-treated); 8 will be treated and survive. Their breast cancer would have caused a problem if left untreated; 4 will be treated but die. Of the 200 women screened, 185 will not be diagnosed with breast cancer; 15 will be diagnosed with breast cancer; 3 will be treated but their breast cancer would not have caused a problem anyway (over-treated); 9 will be treated and survive. Their breast cancer would have caused a problem if left untreated; 3 will be treated but die. Meaning that out of 200 women, 3 will be over-treated due to screening.

The numbers given are based on estimates made by experts using the best data available and have been rounded up for simplicity.

In 2015-16, more than seven out of every 10 women invited for breast screening chose to attend.

Things you may wish to consider:

  1. Breast screening can prevent women dying from breast cancer: For every 200 women who go for screening every three years from ages 50 to 70, about 15 will be diagnosed with breast cancer and 12 will survive. That’s one extra woman whose death from breast cancer is prevented compared with 200 women who don’t go for screening.
  2. Sometimes extra tests are needed to check an abnormal area: About four out of every 100 women who go for a mammogram appointment are asked to have more tests. Having extra tests can be a worrying time. On average, three of these women are reassured they don’t have breast cancer. One does have breast cancer.
  3. Most women receive assurance that they don’t have breast cancer: For every 200 women who go for screening every three years from age 50 to 70, about 185 will be told they don’t have breast cancer. Some will need to have extra tests to confirm this at some point, while others will only ever need routine mammograms.
  4. Very rarely, mammogram X-rays can cause cancer: Women who attend routine breast screening every three years for 20 years have a very slightly increased risk of developing cancer at some point in their life.
  5. If a breast cancer is spotted through screening, there’s a chance of over-treatment: For every 200 women who go for screening every three years from ages 50 to 70, about 15 are diagnosed with breast cancer. It is estimated that about three have treatment for a cancer that would not have caused problems, while 12 receive treatment they needed. It’s not possible to confirm which women are over-treated.
  6. Occasionally, mammograms miss breast cancer: Occasionally, a mammogram can miss a sign of breast cancer. Breast cancers can also develop between breast screening appointments.
  7. If you have cancer, a mammogram means you’ll know and might be treated sooner: For every 200 women who go for screening every three years from ages 50 to 70, about 15 are diagnosed with breast cancer, and might start treatment sooner than they otherwise would.
  8. Mammograms can cause discomfort or pain: Most women experience some passing discomfort or pain during their mammogram. Some women say that the pain they experienced would stop them going again in the future.
  9. Choosing not to attend breast screening doesn’t increase your risk of getting breast cancer: You are not more likely to get breast cancer if you don’t go for breast screening. Mammograms can help to spot cancers earlier, but they don’t stop cancers developing. It is important to check your breasts regularly, whether or not you go for breast screening.

Breast screening: deaths from breast cancer prevented and over-treatment

Of 200 women who don't attend breast screening (ever 3 years from age 50 to 70): 12 are diagnosed with breast cancer; 8 are treated and survive; 4 are treated but die. Of 200 women who do attend breast screening (every 3 years from age 50 to 70): 15 are diagnosed with breast cancer; 12 are treated and survive; 3 are over-treated; 3 are treated but die.

Who can help you make your choice

To help you decide whether to go for breast screening, think about each of the benefits and risks – which things are most important to you?

You may wish to talk through the decision with:

  • your doctor
  • your breast screening service
  • family and friends.

Whatever you decide, remember that you can change your mind in the future. If you decide to go, simply turn up at the screening unit at the time they have given you, or call the service if you wish to change the appointment time.

If you decide not to go, tell the screening service so they can offer the appointment to someone else. They will invite you again in three years’ time.

Whether or not you go for breast screening, it’s important to be breast aware. This means knowing what your breasts look and feel like normally, being on the lookout for any unusual changes and getting them checked by your doctor. Find out more about how to be breast aware.

Breast Cancer Now believes that if we all act now, by 2050, everyone who develops breast cancer will live. NHS breast screening can prevent women dying from breast cancer. It is estimated that breast screening prevents about 1,300 deaths from breast cancer every year in the UK, and the more women who attend, the more deaths can be prevented. For this reason, Breast Cancer Now supports the NHS breast screening programme and we encourage women to attend.

We know that breast screening has some risks too. The greatest of these is the chance that women will receive treatment for an early breast cancer (DCIS) that would never have grown and caused problems.

In the longer term, we hope that better tests will become available so that doctors can more accurately predict which cancers will or won’t grow. Our researchers are working on this.

For the moment, evidence shows us that for most women who attend breast screening, the potential benefits outweigh the risks.

We think that it’s important that every woman invited has the information she needs to confidently decide whether to attend.

Whether or not you attend breast screening is your choice. We hope that this web resource has helped you to learn more about breast screening and make a decision.

If you missed your breast screening appointment or the time you are offered doesn’t suit you, you can contact your local screening unit to rearrange your appointment. Contact details can be found on your invitation letter or on the NHS Choices website

People affected by breast cancer are at the heart of Breast Cancer Now’s health information. We want our facts about breast cancer risk, breast awareness, diagnosis, treatment and services to give you the knowledge and confidence you need to make decisions about your health and health care.

Our screening guide is based on up-to-date research evidence, evidence from the NHS screening service and estimates made by experts. All numbers have been rounded up for simplicity. All information was reviewed by appropriate experts and members of the public.

We advise people with concerns about screening or breast cancer to discuss them with a health professional.

If you would like more information about the sources of evidence on which this guide is based, or have any suggestions on how to improve our guide, please email us at info@breastcancernow.org or call 0333 20 70 300.

Last reviewed: April 2016

Next review due: April 2019

Breast Cancer Now's health information is covered by NHS England's Information Standard quality mark. Find out more.

We hope this information has helped you make a choice. If you have any further questions, please contact us on info@breastcancernow.org or 0333 20 70 300.