Family History, Mutation Location Increase Risks of Breast, Ovarian Cancers

Researchers investigating the risks of breast, ovarian, and contralateral breast cancer for mutation carriers found that family history and mutation position are important for determining cancer risk estimates, according to a study published in JAMA.

The prospective cohort study included analysis of 7666 female carriers from the BRCA1/2 Carrier Cohort Study, 1570 mutation carriers from the Breast Cancer Family Registry, and 620 mutation carriers from the Kathleen Cunningham Foundation Consortium. The analysis of each consortia concluded with a follow-up in December 2013.

Breast and ovarian cancer risks were determined through baseline and follow-up questionnaire answers. If a woman did not have any cancer at baseline, then was diagnosed with breast or ovarian cancer during the follow-up, the study considered her as affected. Contralateral breast cancer patients were included in the analysis if their follow-up was at least 1 year following their first breast cancer diagnosis and they were diagnosed with asynchronous contralateral breast cancer during the follow-up.

Of the 3886 eligible BRCA1 and BRCA2 mutation carriers, 426 were diagnosed with breast cancer. The cumulative risk of developing the disease by age 80 of 72% for BRCA1 and 69% for BRCA2. While considering ovarian cancer risk, 109 of 5066 women were diagnosed.

The cumulative risk of developing ovarian cancer by the age of 80 was 44% for BRCA1 carriers and 17% for BRCA2 carriers. Out of the 2213 women in study for asynchronous contralateral breast cancer, 245 were diagnosed. The study noted a higher risk of the disease when the first breast cancer is diagnosed before the age of 40; however, the risk is decreased with adjuvant treatment of the first cancer.

Family history and mutation location was also associated with cancer risk in the study. The results suggested that women with no family history have lower risks of being diagnosed with cancer; however, the study noted the selection bias and lack of family size consideration in the data. According to the study, mutation location demonstrates a higher risk or lower if the mutations lie in certain genes that are associated with breast or ovarian cancer.

“These findings provide information on cancer risk for BRCA1 and BRCA2 mutation carriers using prospective data and demonstrate the potential importance of family history and mutation location in risk assessment,” the authors concluded.