About one in eight women in the UK are diagnosed with breast cancer during their lifetime. There's a good chance of recovery if it's detected in its early stages.
Breast screening aims to find breast cancers early. It uses an X-ray test called a mammogram that can spot cancers when they are too small to see or feel.
Breast screening does, however, have some risks you should be aware of (see below).
As the likelihood of getting breast cancer increases with age, all women who are aged 50-70 and registered with a GP are automatically invited for breast cancer screening every three years.
In the meantime, if you are worried about breast cancer symptoms, such as a lump or area of thickened tissue in a breast, don't wait to be offered screening – see your GP.
This page gives an overview of breast cancer screening, with links to information on why and when it is offered, what happens when you go for breast screening, and receiving your results.
Most experts agree that regular breast screening is beneficial in identifying breast cancer early. The earlier the condition is found, the better the chances of surviving it.
The main risk is that breast screening sometimes picks up cancers that may not have caused any symptoms or become life-threatening. You may end up having unnecessary extra tests and treatment.
Read about the pros and cons of breast cancer screening.
Breast screening is currently offered to women aged 50-70 in England. However, the NHS is in the process of extending the programme as a trial, offering screening to some women aged 47-73.
You will first be invited for screening between your 50th and 53rd birthday, although in some areas you'll be invited from the age of 47 as part of the trial extension of the programme.
You may be eligible for breast screening before the age of 50 if you have a higher-than-average risk of developing breast cancer (for more information, read 'If you have a family history of breast cancer').
If you're over the age of 70, you'll stop receiving screening invitations. However, you're still eligible for screening and can arrange an appointment by contacting your local screening unit.
For more information, read when breast cancer screening is offered.
Breast screening is carried out at special clinics or mobile breast screening units. The procedure is carried out by female members of staff who take mammograms.
During screening, your breasts will be X-rayed one at a time. The breast is placed on the X-ray machine and gently but firmly compressed with a clear plate. Two X-rays are taken of each breast at different angles.
For more information, read what happens during breast cancer screening.
After your breasts have been X-rayed, the mammogram will be checked for any abnormalities. The results of the mammogram will be sent to you and your GP no later than two weeks after your appointment.
Following screening, about one in 25 women will be called back for further assessment. Being called back doesn't mean you definitely have cancer. The first mammogram may have been unclear.
About one in four women who are called back for further assessment are diagnosed with breast cancer.
Read our page on understanding your results.