The role of screening mammography in the era of modern breast cancer treatment.

The evidence is reviewed on the efficacy and effectiveness of mammography screening derived from randomized screening trials and from the surveillance of populations where mammography screening for breast cancer has been introduced. Nearly all the trials were performed in the era before modern adjuvant therapy for breast cancer was introduced, apart from the Canadian National Breast Screening Study and the UK Age trial. The former found no benefit from annual mammography screening for 5 years in women age 40-59 years, the latter, a non-significant benefit from screening women by annual mammography for 7 years from ages 39 to 41 years. The evidence from population-based surveillance is mixed, most such studies having failed to consider the benefit gained from improved therapy. It is concluded that we have reached the point of negligible benefit from mammography screening for breast cancer in women at average risk, and that we should concentrate on early diagnosis of breast cancer and the application of modern therapy according to clearly defined sub-types of breast cancer.