At present in the UK, the screening programme is aimed at women between 50 and 70, though this will shortly be extended to women over 47. If you are more at risk, for instance through previous problems or having a close relative with breast cancer, you may need to be screened earlier. Screenings are normally recommended every three years.

Between 2009 and 2010 the UK screening programme detected over 70,000 cancers that would not otherwise have been found. While it's important to carry out your own check at home every month, self-examination can only find a cancer that has already developed far enough to be felt, for example as a lump, whereas a mammogram can detect them earlier.

The main downside is the exposure to radiation, though the amounts are small. There have also been cases of overdiagnosis, where something may have been removed unnecessarily, but these are outweighed by the cases where harmful cancers have been detected.

You can learn more about the programme here, and if you scroll down the page you will find several informative leaflets. The first of these clearly lists the pros and cons of screening.