Screening is the assessment of asymptomatic individuals in an effort to detect a serious condition at an early stage for which early intervention is beneficial.

Breast screening was introduced in the UK in 1988 following the recommendations of the Forrest Report, based on a review of the available evidence at the time. Quality assurance was introduced as part of the screening process which has had beneficial effects on the evolution of symptomatic breast practice and beyond. Women are invited for mammography every 3 years between the ages of 50 and 70 years. Two views of each breast are taken at the first visit with reading of films by two radiologists. If the film is unsatisfactory or abnormal, the patient is recalled for further assessment in the screening service and further imaging and/or biopsy is performed.

Breast screening saves 1400 lives per year at a cost of £30,000 per year of life saved. For every 400 women screened over a 10-year period, it is calculated that one fewer women dies from breast cancer than would have died had they not been screened. This equates to 1 in 8 fewer breast cancer deaths in the target age group. Success of breast screening is difficult to quantify and vocal critics of the process exist. Approximately 1 in 8 women with cancer diagnosed by screening would never have had their cancer diagnosed if they had not undergone screening. Over a 10-year period, 1 in 8 of all women screened will be recalled at least once. The breast screening process has changed the pattern of breast cancers seen with many more small, low-grade cancers and preinvasive lesions now being diagnosed and treated.