Women who carry a BRCA1 or BRCA2 mutation are 9 to 36 times more likely to develop breast cancer than women without the mutation, and 6 to 61 times more likely to develop ovarian cancer. But to assess the degree of increased ovarian cancer risk in women with a family history of breast cancer who do not carry the genetic mutation, researchers at Memorial Sloan-Kettering Cancer Center followed 199 families with a strong family history of breast cancer but who were BRCA mutation-negative.

Forty months (equivalent to 2,534 years of follow-up) after genetic testing to determine their BRCA status, only one case of ovarian cancer was diagnosed, considered normal for women at average risk. But 19 new cases of breast cancer were found, when only six were anticipated. "The study was actually designed to look at these women's subsequent risk of ovarian cancer, which was not elevated compared to women in the general population," explains lead author Noah D. Kauff, MD. "The fact that these women had a three-fold higher risk of breast cancer than women in the general population was not surprising, as the women in our study were selected from inherited breast cancer families." But the research provides the first prospective evidence that women with a strong family history of breast cancer who do not have the genetic mutation are not at increased risk for ovarian cancer. "These results need to be confirmed in a larger study with longer follow-up," says Dr. Kauff. "If they are confirmed, it will allow for (re-)tailoring of ovarian cancer risk-reduction strategies for women with a family history of breast cancer but with no identifiable BRCA mutation." The study appeared in a recent issue of the Journal of the National Cancer Institute.