New Study Reveals Even Without BRCA, Strong Family History of Breast Cancer Increases Risk

Women who grow up with a family history of breast cancer say that knowledge is like "a dark cloud hanging overhead" or "a time bomb ticking." Now studies indicate their feelings are based in reality, even when genetic testing shows they are negative for BRCA1 or BRCA2.

Kelly Metcalfe, an associate professor of nursing at the University of Toronto, is the author of the new study released Monday, which indicates that women with a strong family history of breast cancer are four times more likely to be diagnosed with the disease than women in the general population; for those who are under 40, that risk is 15 times greater than the general population.

An article in US News & World Report details the study and its findings:

To be included in the Canadian study, women had to have two or more relatives diagnosed with breast cancer before the age of 50 or three relatives with breast cancer at any age.

The researchers compared the rates of breast cancer among these women with a family history against rates found in the general population based on regional cancer registries.

Over the follow-up period, 15.2 of the women in the family history group would have been expected to get breast cancer, but 65 did -- a fourfold increased risk. Women with family histories who were under the age of 40 had a 15-fold higher risk, the researchers found.

To put these risks in perspective, Metcalfe said a typical woman who tests positive for BRCA1 or 2 has an 80 percent lifetime risk of getting breast cancer, while women such as those in her study with a strong family history but no BRCA1 or 2 mutation have about a 40 percent lifetime risk. The average woman has about a 10 percent lifetime risk of developing breast cancer, she said.

While other studies have found similarly increased risks of breast cancer among women with a strong family history, the current study adds to the information, Metcalfe said. "What we were able to observe were the differences in age," she said.

Related article: With a Family History of Breast Cancer, She Chose a Prophylactic Double Mastectomy