Risk of prostate cancer is highest if brother is affected

Brothers of men with prostate cancer have almost three times the risk of developing the disease as men with no family history of it, researchers have found. The son of a man with the cancer has slightly more than twice the risk, which is almost the same as a second-degree relative, such as an uncle or grandfather.

It’s been known that having a brother or father increased cancer risk, but this study -- an analysis of 23 other prostate cancer-risk studies -- was the first to show a statistically higher risk when the brother is affected.

The findings indicate that some environmental factors are involved along with a genetic predisposition. Brothers usually grow up in the same place, eating the same food and exposed to the same air and water; fathers and sons do not.

“Having a shared environment may play a larger role than it does in women with breast cancer, which is the gold standard at the moment in studying the influence of heredity,” says lead author Deborah Watkins Bruner, director of the prostate cancer risk-assessment program at Fox Chase Cancer Center in Philadelphia. Inheriting a breast cancer-related gene from the mother puts the daughter at very high risk for breast cancer.

“We may never find the equivalent gene for prostate cancer,” Bruner says. “Rather, there may be multiple genes involved.” This study was published online Sept. 12 in the International Journal of Cancer.

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-- Dianne Partie Lange