Long-term benefits of breast screening

A series of prospective randomized controlled trials of breast cancer screening convincingly demonstrated the efficacy of an invitation to mammography to reduce breast cancer deaths. Evaluation efforts since then have focused on the absolute benefit of breast cancer screening overall and in age-specific subgroups, with various measures of benefit versus harm, and an interest in the degree to which improvements in therapy and women's improved reporting of symptoms have eclipsed some or all of the benefit of detection of occult disease by mammography. In this article we describe the summary measures of the efficacy of mammography demonstrated by the randomized controlled trials, the importance of long-term follow-up to measure the absolute benefit of mammography and the balance of benefits and harms, including the number needed to screen to save one life and overdiagnosis.