Early radiation exposures and BRCA1-associated breast cancer in young women from Poland

Abstract

1525 Background: Ionizing radiation is an established risk factor for breast cancer in young women. There is concern that early radiation exposure might pose a risk to women who are genetically predisposed. Several of the genes that are involved in cancer susceptibility function in the DNA damage response pathway, including BRCA1, which is critical for the repair of damage of the type induced by ionizing radiation. Methods: To study whether or not there is an adverse effect of early chest x-rays on breast cancer risk in BRCA1 carriers, we compared the histories of chest x-ray exposures before age 30 in 138 BRCA1 carriers with breast cancer with 158 age- matched women with breast cancer, but without a BRCA1 mutation. All cases were drawn from a national breast cancer research registry. Results: Affected carriers reported more frequent chest x-ray use before age 20 than affected non-carriers (0.6 versus 0.3; p = 0.01). Affected carriers had, on average, 1.8 chest x-rays before age 30 compared to an average of 1.0 for affected non-carriers (p = 0.002). The odds ratio for ever having had a chest x-ray below age 30, given a BRCA1 mutation, was 1.8 (95% CI = 1.2 to 2.9; p = 0.01). Conclusions: These observations support the hypothesis that early radiation exposure may be a risk factor for breast cancer in BRCA1 carriers. No significant financial relationships to disclose.