Diagnostic Radiation, BRCA1/2 Mutations, and Breast Cancer Risk

The genes BRCA1 and BRCA2 are involved in repairing DNA breakage, which can be caused by ionizing radiation. Does exposure to diagnostic radiation (e.g., chest radiography, mammography) raise risk for breast cancer in BRCA1/2 mutation carriers? In this European retrospective cohort study, investigators estimated such risk in 1993 women with BRCA1/2 mutations. Questionnaire responses were used to estimate cumulative doses of breast irradiation.

In all, 43% of participants had diagnosed breast cancer. Compared with no exposure to diagnostic radiation, any exposure before age 30 was associated with higher breast cancer risk (hazard ratio, 1.9) that rose with radiation dose; the HR at the highest estimated cumulative dose was 3.8.