Age at initiation of screening mammography by family history of breast cancer in the breast cancer surveillance consortium

Purpose Women with a first-degree family history of breast cancer (FHBC) are sometimes advised to initiate screening mammography when they are 10 years younger than the age at which their youngest relative was diagnosed, despite a lack of unambiguous evidence that this is an effective strategy. It is unknown how often this results in women initiating screening earlier (< 40 years) than screening guidelines recommend for average-risk women. Methods We examined screening initiation age by FHBC and age at diagnosis of the youngest relative using data collected by the Breast Cancer Surveillance Consortium on 74,838 first screening mammograms performed between 1996 and 2016. Results Of the 74,838 women included in the study, nearly 9% reported a FHBC. Approximately 16.8% of women who initiated mammography before 40 years reported a FHBC. More women with a FHBC than without initiated screening < 40 years (48% vs. 23%, respectively). Among women with a FHBC who initiated screening < 40 years, 65% were 10 years younger than the age at which their relative was diagnosed. Conclusion Women with a first-degree relative diagnosed with breast cancer were more likely to start screening before 40 years than women reporting no FHBC, especially if their relative was diagnosed before 50 years.