Increased Risk of Developing Breast Cancer after a False-Positive Screening Mammogram.

BACKGROUND Women with a history of a false-positive mammogram result may be at increased risk of developing subsequent breast cancer. METHODS Using 1994 to 2009 Breast Cancer Surveillance Consortium data, we included women ages 40 to 74 years with a screening mammogram that resulted in a false-positive with recommendation for additional imaging, false-positive with recommendation for biopsy, or true-negative with no cancer within one year following the examination. We used partly conditional Cox proportional hazards survival models to assess the association between a false-positive mammogram result and subsequent breast cancer, adjusting for potential confounders. Adjusted survival curves stratified by breast density and false-positive result were used to evaluate changes in risk over time. RESULTS During 12,022,560 person-years of follow-up, 48,735 cancers were diagnosed. Compared with women with a true-negative examination, women with a false-positive with additional imaging recommendation had increased risk of developing breast cancer [adjusted HR (aHR) = 1.39; 95% confidence interval (CI), 1.35-1.44] as did women with a false-positive with a biopsy recommendation (aHR = 1.76; 95% CI,1.65-1.88). Results stratifying by breast density were similar to overall results except among women with almost entirely fatty breasts in which aHRs were similar for both the false-positive groups. Women with a false-positive result had persistently increased risk of developing breast cancer 10 years after the false-positive examination. CONCLUSION/IMPACT Women with a history of a false-positive screening mammogram or biopsy recommendation were at increased risk of developing breast cancer for at least a decade, suggesting that prior false-positive screening may be useful in risk prediction models.