Breast Screening Mammography
All women in the UK who are aged between 50 and 70 are invited to a breast screening test every three years to look for early signs of breast cancer.
What is breast screening?
Breast screening aims to detect breast cancer at an early stage, before symptoms or signs develop, such as a lump. Breast screening involves having an X-ray picture of each of your breasts, which is called mammography.
If breast cancer is found early, it is more likely that you will be able to have breast-conserving surgery (hopefully avoiding a mastectomy). It is also more likely that you will have a greater chance of surviving the breast cancer in the long term.
Who has breast screening?
Currently, all women aged 50-70 years in the UK are offered a routine breast screening test (mammogram) every three years. More than 2 million women are screened in the UK each year.
In some parts of the UK, a trial is being done to see if screening would benefit women from age 47 to 73. So in these areas, you may receive an invitation before the age of 50, or after the age of 70.
Otherwise if you are under the age of 50, routine breast screening is not currently available unless:
- You have had breast cancer in the past.
- You have a mother or sister (first-degree relative) who has had breast cancer at a young age.
- You have two or more relatives who have had breast cancer. (Exact rules for screening depend upon the age at which your relatives were diagnosed with breast cancer.)
- You have a father or brother (first-degree male relative) who has had breast cancer at any age.
- You are known to have a gene which makes you more prone to breast cancer, such as genes called BRCA1, BRCA2 and TP53. (Most women will not know their genetic makeup but some women have genetic tests for various reasons.)
If you are unsure whether you should be screened from an earlier age then see your GP.
What age does breast screening stop?
In some areas, all women between the ages of 47 and 73 will be invited for breast screening as part of a trial. However, unless these results show benefit in due course, this will not be extended to all areas of the UK.
In the meantime, if you are over 70, you may still consider having breast screening every three years. You will not receive an automatic invitation; however, you are entitled to this as a free service. If you wish to have breast screening over the age of 70, contact your local breast screening unit to make an appointment by phone or by letter. Ask at your GP surgery for details of your nearest breast screening unit.
How does breast screening work?
Mobile screening units
There are many breast screening units throughout the UK, where your mammogram test will be done. Some are at hospitals but many of the units are mobile and move from area to area. An invitation for breast screening will usually arrive by post, giving you the date, time and place to attend. If this is inconvenient for you, you can telephone to change the appointment. You may also be able to change it by completing a form online.
The breast screening programme is a rolling programme. Women from different GP practices are invited in turn. This means that you may not receive an invitation for screening as soon as you are 50. However, you should receive your first invitation before your 53rd birthday.
When you attend the unit you will be asked to undress down to your waist, including removing your bra. Therefore, it is best to wear a skirt or trousers and a top. A radiographer will help to position each breast between two flat X-ray plates. This can be a little painful but is usually only for a few seconds as the X-ray picture is taken. In some women, the pain may persist for a short time afterwards. Two breast X-rays are taken (one from above and one into the armpit diagonally across the breast). The whole appointment usually takes about 30 minutes. The result of the test is sent to you and your GP. Screening results generally take about two weeks.
The administration of breast screening is a large exercise. Problems can sometimes lead to errors, such as if you move to a different area or you change your surname. Tell your GP if you did not receive the result of your test or if you have not been invited to attend in the last three years and you are in the screening age range.
If you have had breast implants, you can still have breast screening. This may be done in a hospital-based screening unit. Let the unit know you have implants before the appointment.
What if there is an abnormality?
Most women have a normal test result. However, between 3 and 8 in 100 women are asked to attend again for further more detailed tests. If it is your first screening test, it is more common to be asked to attend again. This may be because the X-ray picture is not clear, or to look more closely at a particular area of the breast. This is obviously a concern, but only about 19 out of every 100 women called back for further tests actually have cancer. In the rest, the shadows, marks or other abnormalities that are detected in the screening test turn out to be harmless.
In some cases more tests are needed to determine if there is a problem. This will usually be done in a specialist breast clinic. You would have an examination of your breasts by a breast specialist nurse or doctor. You may have to have an ultrasound scan or further mammograms. In some cases a sample of the suspect area may be drawn out with a needle for further analysis. In others a biopsy may be required.
And remember, if it does turn out to be cancer, it is likely to be an early cancer when there is a good chance of successful treatment.
What is the benefit of breast screening?
Now that breast screening has been done for some time, a number of studies have reviewed the benefits as compared to the possible harms. The results have varied.
It saves lives
An independent review in the UK in 2012 concluded that breast screening does save lives. If 10,000 women are screened from when they are 50 to when they are 70, around 43 deaths would be prevented. This would mean screening prevents about 1,300 deaths every year in the UK. A 2013 international review (Cochrane review) concluded that for 2,000 women screened for 10 years, one will avoid dying of breast cancer.
Most international reviews agree that there is evidence that some deaths from breast cancer are prevented by screening. However, another study in Canada which looked at results of 25 years of breast screening, found no convincing evidence that screening prevents deaths.
Are there any risks with breast screening?
Having a mammogram is a fairly reliable way of screening for breast cancer. However, as with any screening test, it is not perfect. There has been some controversy about breast screening, with some people suggesting the possibility that it may do more harm than good for some women. Some of these concerns are discussed here.
There is concern about the over-diagnosis of breast cancer. This refers to breast cancers that are detected through screening that would not have been diagnosed without screening, but would not have threatened the lives of the women screened.
Once diagnosed through screening, these cancers have to be treated. This is because it is not currently possible to predict which cancers found through screening will develop aggressively and which will grow very slowly.
So, without screening, a proportion of women would never have been treated for breast cancer. They would never have known that they had breast cancer in their lifetime and would have died from other causes.
In the UK independent review mentioned above, it was concluded that for the 10,000 women screened from when they are 50 to 70, 129 women would be over-diagnosed. The Cochrane review found that for the 2,000 women screened over 10 years, 10 women would have unnecessary treatment. In this analysis, for every life saved, ten women would have treatment which was not necessary. In the UK, the NHS breast cancer screening programme estimates that for every one life saved, three women have treatment that they didn't need.
Some women become very anxious if they are recalled for further tests following the screening test because of concerns about an abnormality. However, over three quarters of the women who are recalled for further tests do not have cancer. Some people argue that these women are put through this anxiety and these further tests unnecessarily because, without screening, they would not have needed these further tests.
Risk of radiation from the X-ray
Some people worry about the risk of radiation from the X-ray screening test and that it may be harmful and even increase the risk of breast cancer. However, the amount of radiation used is small and the risk of the X-ray test itself being harmful is very small indeed. One study found that breast cancer caused by radiation from X-rays happens to 1 to 10 out of each 100,000 women screened.
Missed cancers (false negatives)
Also, very occasionally, breast screening may miss some breast cancers. This may be because the cancer is very difficult to see on the mammogram (some cancers cannot be seen at all), or the person reading the mammogram may miss the cancer. (This can even happen with the most experienced of people.)
Based on the evidence currently available (which includes a 2021 review by the European Commission), the benefits of detecting breast cancer early for average-risk women between the ages of 50-69 outweigh any harm from breast screening because of the number of lives saved.
The evidence for women outside that age range is less clear. Decisions about screening for women with higher than average risks, who are outside that age range, should be taken on an individual basis with your doctor.
MRI breast screening
It has been suggested that scanning using magnetic resonance imaging (MRI) may be better than mammography as a way of screening for and detecting early breast cancer in certain groups of women. For example, those who are at high risk of developing breast cancer, perhaps because they have a strong family history of breast cancer. However, the effect that using MRI scanning as a screening test has on actually reducing the number of deaths due to breast cancer is uncertain.
In the UK, the National Institute for Health and Care Excellence (NICE) has advised that some women who have a high risk of breast cancer may be screened using MRI scanning instead of mammography. This may be the case if there is a strong history of breast cancer that runs in your family, particularly if you are known to carry a gene that makes you more prone to breast cancer.
If you have breast cancer in your family and you are uncertain about your risk of developing breast cancer, you should discuss this with your GP. Remember that most women do not develop breast cancer. Even though you may be told that you have a raised or high risk, it does not mean that you will definitely develop breast cancer.
A lot of breast cancers are detected early by breast screening. However, a small number are not. Some women may have developed breast cancer before they have their first mammogram and some may develop breast cancer between mammograms. All women of every age should still remain breast aware. That is, get to know how your breasts and nipples normally look and feel, and any changes that occur before and after your periods.
See your GP if you notice any changes, lumps, or other abnormalities in your breasts or nipples. Don't just wait until your next screening mammography.
Further reading and references
BRCA in breast cancer: ESMO Clinical Practice Guidelines; European Society for Medical Oncology (2011)
Familial breast cancer: classification, care and managing breast cancer and related risks in people with a family history of breast cancer; NICE Clinical Guideline (June 2013 - last updated November 2019)
Breast screening; NICE CKS, May 2022 (UK access only)
Breast cancer - managing FH: Summary; NICE CKS, December 2018 (UK access only)
Canelo-Aybar C, Ferreira DS, Ballesteros M, et al; Benefits and harms of breast cancer mammography screening for women at average risk of breast cancer: A systematic review for the European Commission Initiative on Breast Cancer. J Med Screen. 2021 Dec28(4):389-404. doi: 10.1177/0969141321993866. Epub 2021 Feb 25.