TUESDAY, Jan. 8 (HealthDay News) -- Broad variation exists in breast cancer risk among carriers of BRCA1 and BRCA2 gene mutations, although risk among first-degree relatives of carriers is higher when the carrier's cancer is diagnosed at a younger age and when the carrier's cancer is contralateral rather than unilateral, researchers report in the Jan. 9/16 issue of the Journal of the American Medical Association.
Colin B. Begg, Ph.D., of the Memorial Sloan-Kettering Cancer Center in New York City, and colleagues genotyped 2,098 breast cancer patients (1,394 unilateral and 704 contralateral) whose cancer had first been diagnosed before age 55. Participants were interviewed and filled out questionnaires regarding familial breast cancer incidence.
The researchers found that among patients with unilateral breast cancer, 73 (5.2 percent) were identified as carriers of BRCA1 or BRCA2 mutations (42 and 31, respectively), while among those with contralateral breast cancer, 108 (15.3 percent) were identified as carriers (67 with BRCA1 and 41 with BRCA2). The report also indicates that among relatives of carriers, risk was significantly associated with younger age at diagnosis of the carrier, and there was a trend toward higher risk when the carrier had contralateral versus unilateral breast cancer.
"Regardless of whether risk variation within BRCA1 and BRCA2 contributes meaningfully to the overall risk variation observed, it seems likely that other genetic factors play a major role," the authors comment.
Abstract
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