(ChemotherapyAdvisor) – Carriers of the common Jewish genetic mutation 6174delT had a 65% lower risk of breast cancer than BRCA2 carriers who did not carry this mutation, a study in the Journal of Clinical Oncology appearing online March 19 concluded.

Mutations in BRCA1/2 have been found to increase risk of both breast and ovarian cancers. In Ashkenazi Jews, three mutations in these genes — 185delAG, 5382insC, and 6174delT — occur at high frequency; the investigators evaluated how these common Jewish genetic mutations might affect cancer risks and risk reduction.

Risk of breast and ovarian cancer was estimated in a cohort of 4,649 women with disease-associated BRCA1/2 mutations from 22 centers in the Prevention and Observation of Surgical End Points Consortium; 969 self-identified as Jewish. Risk reduction from risk-reducing salpingo-oophorectomy (RRSO), by common Jewish mutations, and self-identified Jewish status were also evaluated.

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A common Jewish genetic mutation was found in 91% of Jewish women who were BRCA1/2-positive. Jewish women were significantly more likely to undergo RRSO than non-Jewish women (54% vs. 41%, respectively; OR, 1.87); however, no significant difference was seen in cancer risk reduction after RRSO among subgroups.

“Consistent with previous results, risks for breast and ovarian cancer varied by common Jewish genetic mutation in BRCA1/2 carriers,” the investigators concluded. “This finding requires additional confirmation in larger prospective and population-based cohort studies before being integrated into clinical care.”