(January 31, 2014)  A new study conservatively estimates that one in five women with ovarian cancer has inherited genetic mutations that increase the risk of the disease, according to research at Washington University School of Medicine in St. Louis.

Most women in the study would have been unaware of a genetic predisposition to ovarian cancer because they didn’t have strong family histories that suggested it.

The research, published Jan. 22 in Nature Communications, is the first large-scale analysis of the combined contributions of inherited and acquired mutations in a major cancer type. The inherited mutations by themselves are unlikely to cause ovarian cancer but may conspire with other genetic changes acquired over a woman’s lifetime to tip the balance toward cancer, the researchers said.

Earlier studies that have looked at inherited susceptibility to ovarian cancer have focused on women with known family histories of the disease. For the current study, however, the researchers studied tumors from 429 women with ovarian cancer. Their cases were selected without regard to whether the women had family histories of breast cancer, ovarian cancer or rare cancer syndromes, all of which can increase the odds of developing ovarian tumors.

In all, the scientists identified 222 inherited genetic variants that increase the risk of ovarian cancer. Some occurred in genes already known to be associated with a genetic predisposition to ovarian cancer, such as BRCA1and BRCA2, while others occurred in genes that have never been linked to the disease.

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