Anouk Pijpe, Ph.D., from the Netherlands Cancer Institute in Amsterdam, and colleagues conducted a retrospective cohort study to estimate the risk of breast cancer associated with diagnostic radiation in 1,993 female BRCA1/2 mutation carriers, recruited from 2006 to 2009.

The researchers found that there was a significantly increased risk of breast cancer with any exposure to diagnostic radiation before age 30 (hazard ratio, 1.90), with evidence of a dose-response pattern. The risks by quarter of estimated cumulative dose increased from 1.63 for <0.0020 Gy (95 percent confidence interval [CI], 0.96 to 2.77) to 3.84 for ≥0.0174 Gy (95 percent CI, 1.67 to 8.79). Compared with no exposure, there was an increasing risk with increasing number of radiographs before age 20 and before age 30, based on analysis of the different types of diagnostic procedures. An increased risk of breast cancer was seen for those with a history of mammography before age 30 (hazard ratio, 1.43; 95 percent CI, 0.85 to 2.40). This finding was not due to confounding by indication of family history.

"In this large European study among BRCA1/2 mutation carriers, exposure to diagnostic radiation before age 30 was associated with an increased risk of breast cancer, at dose levels considerably lower than those at which increases have been found in other cohorts exposed to radiation," the authors write. "The results of this study support the recommendation to use non-ionizing radiation imaging techniques (such as magnetic resonance imaging) as the main tool for surveillance in young BRCA1/2 mutation carriers."

One author disclosed financial ties to the life sciences industry; one author receives royalties from BRCA1 testing.

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