When cancer is a family affair

In life’s genetic lottery, we often inherit unfavorable characteristics. Some, like mom’s wiry hair, are innocuous, but certain defective genes can slowly wreak biological damage over time. In two such genes, BRCA1 and BRCA2, mutations predispose their carriers to developing cancers, especially breast and ovarian cancers.

To determine how prevalent and risky BRCA mutations are, Harvey A. Risch, M.D., Ph.D., professor of epidemiology, and colleagues in Ontario, Canada, asked ovarian cancer patients to report the incidence of cancers among their first-degree relatives. The patients were tested for BRCA1/2 mutations, which were correlated with the family histories.

In the December 6 issue of the Journal of the National Cancer Institute, the team estimates that BRCA1/2 mutations lurk in 1 of every 99 individuals (1.01 percent) in the general population—a much higher frequency than previously thought—and that carriers are 4.6 to 102 times more likely than noncarriers to develop ovarian, testicular, pancreatic and female and male breast cancers.

“Families with appreciable histories of any cancers, not just breast and ovary and not just cancers in females, should think about mutation screening because methods of prevention are becoming available,” Risch says.