A set of investigations aimed at the early detection of breast cancer. It includes self-screening by monthly examination of the breasts, and formal programmes of screening by x-ray mammography in special clinics. In the UK the NHS offers regular mammography examinations to all women between 50 and 70 years of age at 80 special screening units; it is planned to extend screening to those aged 47-80. Younger women are not screened because they have a very low rate of cancer. By 2007, 19 million women had been screened and 117,000 cancers detected. The World Heath Organisation calculates that for every 500 women screened, 1 life is saved by early diagnosis.