Important New (and Tentative) Research on Risks of Mammograms for Women with BRCA Mutations

JCO Early Release, published online ahead of print Jun 26 2006 Journal of Clinical Oncology, 10.1200/JCO.2005.03.3126

Effect of Chest X-Rays on the Risk of Breast Cancer Among BRCA1/2 Mutation Carriers in the International BRCA1/2 Carrier Cohort Study

Purpose: Women who carry germline mutations in the BRCA1 and BRCA2 genes are at greatly increased risk of breast cancer (BC). Numerous studies have shown that moderate to high doses of ionizing radiation are a risk factor for BC. Because of the role of the BRCA proteins in DNA repair, we hypothesized that BRCA carriers might be more sensitive to ionizing radiation than women in the general population.

Patients and Methods: A retrospective cohort study of 1,601 female BRCA1/2 carriers was performed. Risk of breast cancer from exposure to chest x-rays, as assessed by questionnaire data, was analyzed using a weighted Cox proportional hazards model.

Results: In this cohort, any reported exposure to chest x-rays was associated with an increased risk of BC (hazard ratio [HR] = 1.54; P = .007). This risk was increased in carrier women aged 40 years and younger (HR = 1.97; P < .001) and in women born after 1949 (HR = 2.56; P < .001), particularly those exposed only before the age of 20 years (HR = 4.64; P < .001).

Conclusion: In our series of BRCA carriers, we detected a relatively large effect on BC risk with a level of radiation exposure that is at least an order of magnitude lower than in previously studied medical radiation-exposed cohorts. Although part of this increase may be attributable to recall bias, the observed patterns of risk in terms of age at exposure and attained age are consistent with those found in previous studies. If confirmed, the results have important implications for the use of x-ray imaging in young BRCA1/2 carriers.

While this is a retrospective study (people recall their past history) on just one sample, it demonstrates a very strong cancer risk for women who have BRCA mutations. The article argues that the radiation from mammograms is what causes the higher rate of cancer, especially in women who have mammograms when they are under 20 years old. The authors also strongly suggest strongly types of research studies (prospective) are needed to test this hypothesis. However, if someone you know and love has BRCA mutations, this is important information to consider and discuss with your health care professional.

It's also important to note that the authors are not questionning the value of mammograms for the vast majority of women who do not have BRCA mutations.

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.