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ICARE Newsletter Summer 2013

Ask the Expert

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The following question was addressed by Dr. Pal, who is a Clinical Geneticist based at the Moffitt Cancer Center:

Q. Does exposure to radiation increase breast cancer risk in BRCA mutation carriers?

A. A number of studies have been conducted to evaluate whether BRCA mutation carriers may be more prone to radiation-induced breast cancer than women without mutations. Two studies failed to provide convincing evidence about the link between ionizing radiation exposure and breast cancer risk in BRCA mutation carriers.1,2  On the other hand, a large international study including 1601 mutation carriers reported a higher breast cancer risk among women exposed to chest X-rays (hazard ratio (HR): 1.54).  Breast cancer risk was highest among women age ≤ 40 with any x-ray exposure , and women born after 1949 with x-ray exposure before age 20.3  Some of these participants were included in a larger international study of 1993 mutation carriers where age-specific total diagnostic radiation exposure (i.e., chest x-rays, mammography, fluoroscopy, and computed tomography) was estimated from self-reported questionnaire data.4 Results indicated that those exposed before age 30 had an increased risk (HR: 1.90; 95% CI: 1.20-3.00), compared to those never exposed. However, this risk was primarily driven by non-mammographic radiation exposure in women younger than age 20 (HR: 1.62; 95% CI: 1.02-2.58).

Ultimately, it is important to weigh potential risks versus benefits regarding routine use of mammographic screening in conjunction with magnetic resonance imaging (MRI) in BRCA mutation carriers, particularly in women below age 30. As there is no clear evidence to suggest that mammograms significantly increase the breast cancer risk in BRCA mutation carriers at the current time, the main question that remains is whether mammograms are useful prior to age 30. Currently, NCCN guidelines5 recommend annual mammography and MRI screening beginning at age 25 years, although some clinics may hold off on the mammography until age 30 after a balanced discussion of risks versus benefits with patients has occurred.

1. Narod SA, et al. Lancet Oncol 7 (5): 402-6, 2006. 2. Goldfrank D, et al. Cancer Epidemiol Biomarkers Prev 15 (11): 2311-3, 2006. 3. Andrieu N, et al. J Clin Oncol 24 (21): 3361-6, 2006. 4. Pijpe A, et al. BMJ 345: e5660, 2012. 5. NCCN Practice Guidelines 2013; V.2.2013: http://www.nccn.org/professionals/physician_gls/recently_updated.asp.

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