No chest x-rays for BRCA1/2 mutation carriers?

The amount of ionizing radiation conferred by an ordinary chest x-ray significantly increases the already high risk of breast cancer in young women with BRCA1/2 germline mutations, according to a recent international retrospective cohort study.

Researchers from Europe and Canada included 1,600 female BRCA1/2 carriers in their study. They found that any exposure to chest x-rays was associated with an increased risk of breast cancer (HR=1.54; 95% CI; 1.1–2.1). They also calculated that the risk was almost doubled in carrier women 40 years of age and younger (HR=1.97; 95% CI; 1.3–2.9).

The study is particularly significant because the dose of radiation studied is at least an order of magnitude lower than that in other radiation-exposed cohorts studied to date. It is possible that loss of normal BRCA1- or BRCA2-associated DNA repair activity may predispose women who carry mutations in these genes to accumulate radiation-induced genetic damage that accelerates carcinogenesis.

Commentary by Andrew Berchuck, MD, Director of Gynecologic Oncology, Duke University Medical Center, Durham, N.C.:

As the study authors noted, it's possible that the findings of this report could be spurious due to recall bias: Women with breast cancer are more likely to remember radiation exposure than those without cancer. In view of the above issue and other potential pitfalls of retrospective studies, these results need to be confirmed in prospective studies.