Breast screening certainly saves lives. It helps to diagnose breast cancer early, which we know improves the outcome of treatment. But is regular screening doing more harm than good? There’s varying opinion about breast screening – even among the experts – and this can be confusing for women who just want to do the best for their health.

There’s been lots of talk in the media about the risks of breast screening – overdiagnosis, false-positive results, unnecessary cancer treatment and the risk of radiation. But there’s also the fact that around 1,300 breast cancer deaths are prevented every year in the UK thanks to breast screening.* So, in this blog, we’re laying out the benefits and risks of breast screening. Whether or not to have screening is up to you – it can help to find out as much as you can to help decide.

What is breast screening?

Breast screening is a way of finding breast cancers early, when they are too small for you or your doctor to see or feel. The test used for breast screening is a mammogram, which is a breast x-ray. It involves having each breast, in turn, gently but firmly compressed (squashed) with a flat, clear, plastic plate. An x-ray is then taken to get a picture of your breast tissue. Most women find this uncomfortable and some say it’s painful, but it doesn’t take long, and you can go about your normal day again afterwards.

What is the NHS Breast Screening Programme?               

Under the NHS screening programme, all women registered with a GP and aged 50–70 are offered a mammogram every three years. If you’re over 70, you won’t get invitations any more, but you can still have a mammogram every three years.

Each year, more than one and a half million women in the UK have breast cancer screening as part of the NHS Breast Screening Programme.

What are the benefits?

  • It saves lives – around 1,300 in the UK every year.* Women who take part in breast screening have a reduced risk of dying from breast cancer – research trials have estimated that screening can help reduce the risk of dying from breast cancer by 15%.**
  • It finds cancers early – In women who have breast screening, most cancers are found at an early stage when there is a good chance that treatment will be successful.
  • It can avoid the need for a mastectomy – When a breast cancer is found earlier, it’s more likely to be smaller, meaning it can be removed by breast-conserving surgery (a lumpectomy – removal of the lump) rather than a mastectomy (removal of the whole breast). Around 70% of women diagnosed by screening have breast-conserving surgery, compared with 55% of women diagnosed outside the screening programme.***

What are the risks?

  • It involves radiation – All x-rays, including mammograms, involve a small amount of radiation. However, the amount given during a screening is very small and unlikely to cause harm. The risk associated with having a mammogram every three years is considered to be far outweighed by the benefits of detecting a breast cancer at an early stage. 
  • It can give false-positive results – Mammograms can find abnormal areas of tissue that, after further tests, are found not to be cancer. About 1 in 20 women get an abnormal result and are invited to attend a breast assessment clinic for further tests. These may involve scans and biopsies that can cause pain or scarring. This also causes cause a lot of worry and anxiety, although around 7 in 8 women who have further tests do not have breast cancer. ****
  • It can occasionally miss a cancer – A breast cancer may not be detected for various reasons: some cancers are very difficult to see on the x-ray; some cancers can’t be seen on the x-ray; occasionally the person reading the x-ray may make a mistake (to reduce the risk of this happening, all mammograms are looked at by two people).
  • It can diagnose a cancer which never needed treating – The mammogram may find a cancer that would never have caused a problem during the woman's lifetime. It’s not possible to tell which cancers will and won’t cause problems, so women will be offered cancer treatments for any cancer detected. Treatment may include mastectomy (removal of the breast), radiotherapy, hormonal therapy or chemotherapy. These can all cause side effects.

While breast screening certainly saves lives, for every life saved, about three women will have treatment for a cancer that would not have caused them problems.***** 

Independent Breast Screening Review 2012

In response to all the questions about the effectiveness of breast screening and whether women are being given the right information about it, Cancer Research UK worked with the National Cancer Director to set up an independent review of breast screening. Experts weighed up all the evidence about the pros and cons of breast screening. The panel included a breast cancer patient and experts in medical statistics, research and breast cancer treatment.

The Panel concluded that screening reduces breast cancer deaths but at the cost of overdiagnosis. The Panel also concluded that the UK breast screening programme has significant benefit and should continue.

You can read more about the review on Cancer Research UK’s website.

Making decisions about screening

Deciding whether or not to have breast screening isn’t easy, but we hope the information in this blog helps you to weight it all up.

For more information, you may want to order our free booklet, Understanding breast screening.

Breast screening can't pick up every cancer, so you should see your GP if you have any symptoms such as a change in the size or shape of your breast, a breast lump, pain or discharge from the nipples. You should see your GP even if you are having regular breast screening and have recently had a normal mammogram.

And remember, if you ever need to talk or ask a question, our cancer support specialists are here.

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*Findings of the Independent Breast Screening Review, by Cancer Research UK and the National Cancer Director, 2012.
** Gøtzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane Summaries. 2011.
***Benefits of breast screening. Macmillan Cancer Support. ****Disadvantages and risks of breast screening. Macmillan Cancer Support. ***** Findings of the Independent Breast Screening Review, by Cancer Research UK and the National Cancer Director, 2012.