Little is known about the change in mammograms use by women after BRCA1/2 genetic testing. We compared the rate of bilateral mammograms after and prior to BRCA1/2 testing, according to test result. Information from the Quebec Health Insurance Board database was used to identify all registered mammograms delivered between May 1, 1998 and March 31, 2012 to a cohort of 396 unaffected French Canadian women tested for BRCA1/2 mutations. Mammograms incidence density ratios were calculated using the Cox proportional hazards model for repeated events. BRCA1/2 mutation carriers and women with an inconclusive result had more mammograms after, than prior to, genetic testing. Non-carriers did not receive more mammograms. The observed increase in mammography screening in BRCA1/2 carriers is consistent with the high risk of developing breast cancer in this group. The estimation of the cancer risk associated with an inconclusive result is based on familial cancer history, and women who received this result appear to have received follow-up as if at high risk. The fact that non-carriers did not change their use of mammograms after genetic testing may possibly reflect a 'defensive medicine' approach by some physicians or the women's preference.
Keywords: Breast cancer genetic testing; Breast cancer screening; Genes BRCA 1; Genes BRCA 2; Mammography.