Diagnostic radiation studies, especially if done before age 30, increase the risk that women who carry BRCA mutations will develop breast cancer, according to a BMJ study.

Researchers asked some 2000 carriers of BRCA1 or BRCA2 mutations to recall their history of radiation exposure. Based on standard tables, the cumulative radiation dose to the breast was calculated. Compared with no exposure before age 30, the hazard ratios for breast cancer increased with quartiles of increasing cumulative exposure, reaching 3.8 in the highest quartile.

The authors estimate that among 100 BRCA carriers at age 40, roughly 9 will have developed breast cancer. The number would increase by 5 if all had had a mammogram before age 30.

They conclude that their results support using non-ionizing radiation imaging techniques, such as MRI, as the main surveillance tool in young BRCA carriers.

Source: BMJ