Genetic Mutations Carry Different Risks for Breast, Ovarian Cancer

Analysis of cancer-causing mutations in the BRCA1 or BRCA2 genes may lead to more effective treatments.

Cancer-causing gene mutations carry different risks for the development of breast and ovarian cancer, researchers at the University of Pennsylvania recently found.

In a study published in the April 7, 2015 issue of JAMA, investigators evaluated more than 31,000 women to identify mutations in the BRCA1 or BRCA2 genes associated with significantly different risks for breast and ovarian cancers. The results showed that some of the mutations carry higher risks for breast cancer, while other mutations carry higher ovarian cancer risks.

The findings may eventually lead to enhanced cancer risk assessments, in addition to better health care and prevention strategies for both providers and carriers.

"We've made a lot of progress toward understanding how to reduce the cancer risks associated with inherited mutations in BRCA1 or BRCA2 mutations, but until now, little has been known about how cancer risks differ by the specific mutation a woman has inherited," Timothy R. Rebbeck, PhD, associate director for Population Science at Penn Medicine's Abramson Cancer Center, said in a press release. "The results of this study are a first step in understanding how to personalize risk assessment around a woman's specific mutation, which can help guide carriers and providers in the cancer prevention decision making process."

The researchers examined the cancer diagnoses of 19,581 carriers of BRCA1 mutations and 11,900 carriers of BRCA2 mutations to determine if the mutation type or location correlates to cancer risk. Investigators found mutated regions of BRCA1 and BRCA2 that carry a higher risk for ovarian cancer and different regions that carry a higher risk of breast cancer.

Women with a BRCA1 mutation previously were thought to have a 59% risk of breast cancer and a 34% risk for ovarian cancer through 70 years of age. The current study, however, indicates that women with a specific subset of BRCA mutations carry a higher risk of breast cancer at 69% and a lower risk for ovarian cancer at 26%.

The researchers concluded that a key question that remains is whether these differences will alter the decisions women make regarding preventive surgery or other behaviors.

"With these new findings, we've gained knowledge of mutation-specific risks which could provide important information for risk assessment among BRCA1/2 mutation carriers," senior author Katherine L. Nathanson, MD, said in a press release. "Additional research is needed to determine the absolute risks associated with different mutations, and how those differences might influence decision making and standards of care, such as preventive surgery, for carriers of BRCA1 and BRCA2 mutations."