Screening for Breast Cancer: Systematic Evidence Review Update for the US Preventive Services Task Force

BACKGROUND: This systematic review is an update of evidence since the 2002 U.S. Preventive Services Task Force (USPSTF) recommendation on breast cancer screening. PURPOSE: To determine the effectiveness of mammography screening in decreasing breast cancer mortality among average-risk women age 40 to 49 and 70 and older; the effectiveness of clinical breast examination (CBE) and breast self examination (BSE); and harms of screening. DATA SOURCES: Cochrane Controlled Trials Registry and Database of Systematic Reviews (4th Quarter 2008), MEDLINE® (January 2001 to December 2008), reference lists, and Web of Science® for published studies; Breast Cancer Surveillance Consortium for screening mammography data. STUDY SELECTION: Randomized controlled trials with breast cancer mortality outcomes for screening effectiveness; multiple study designs and data sources for harms. DATA EXTRACTION: Investigators abstracted relevant data and rated study quality using established criteria. DATA SYNTHESIS: Mammography screening reduces breast cancer mortality by 15% for women age 39 to 49 (relative risk 0.85; 95% CrI 0.75 to 0.96; 8 trials); data are lacking for age ≥70. Radiation exposure from mammography is low. Patient adverse experiences are common, transient, and do not impact screening practices. Estimates of overdiagnosis vary from 1% to 10%. Younger women have more false positive mammograms and additional imaging, but fewer biopsies than older women. Trials of CBE are ongoing; for BSE, trials showed no reductions in mortality but increased benign biopsies. LIMITATIONS: Studies of older women, digital mammography, and MRI are lacking. CONCLUSIONS: Mammography screening reduces breast cancer mortality for women age 39 to 69; data are insufficient for older women. False positive mammograms and additional imaging are common. No benefit has been shown for CBE or BSE.