After your breasts have been X-rayed, the mammogram will be checked for any abnormalities.
You'll receive a letter with your breast screening results within 2 weeks of your appointment. The results will also be sent to your GP.
There are 3 types of results you can get:
This means the mammogram showed no sign of cancer. You'll be invited to screening again in 3 years.
Remember that cancer can still develop between mammograms, so tell your GP straight away if you notice any breast changes.
Read about the symptoms of breast cancer.
About 96 out of every 100 women screened get a satisfactory result.
The results letter may say you need more tests because the mammogram looks abnormal.
If you're called back for more tests, you may have a breast examination, more mammograms and ultrasounds.
You may also have a biopsy, which is when a small sample is taken from your breast with a needle to be checked under a microscope.
You'll usually get your results within a week.
One in 4 women with an abnormal screening result will be found to have cancer.
The rest won't have cancer and will go back to having screening invitations every 3 years.
Sometimes technical problems mean the mammogram is not clear enough to read.
If this happens, you'll be asked to have another mammogram to get a clearer picture of your breast.
If breast cancer is found, it could be either non-invasive or invasive.
Non-invasive breast cancer
About 1 in 5 women diagnosed with breast cancer through screening will have non-invasive cancer.
This means there are cancer cells in the breast, but they're only found inside the milk ducts (tubes) and haven't spread any further. This is also called ductal carcinoma in situ (DCIS).
In some women, the cancer cells stay inside the ducts. But in others, they'll grow into (invade) the surrounding breast in the future.
Doctors can't tell whether non-invasive breast cancers will grow into the surrounding breast or not.
Invasive breast cancer
About 4 in 5 women diagnosed with breast cancer through screening will have invasive cancer.
This is cancer that's 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.
Read about the treatment of both invasive and non-invasive breast cancer.