Studies: Genes Tied to Breast Cancer Not Linked to Colorectal Cancer

Women with a genetic predisposition to breast or ovarian cancer do not carry the same increased risk of colorectal cancer, according to two studies reported in the Journal of the National Cancer Institute.

Mutations in BRCA1 and BRCA2 genes, which are present in about 2.5 percent of the Ashkenazi Jewish population, have been linked to an increased risk of breast and ovarian cancer, and some earlier studies have suggested an increased risk of colorectal cancer as well..

But in one study, researchers compared the incidence of BRCA1/2 mutations in 586 Ashkenazi Jewish patients with colorectal cancer with that of 5,012 patients with no known history of colorectal cancer, and found no association between the presence of a BRCA mutation and risk of colorectal cancer.

In the second study, University of Michigan researchers performed genetic testing on 1,422 patients with colorectal cancer and 1,566 control subjects without colorectal cancer in Israel, and also found no link.

"We found no strong common genetic basis between colorectal and breast cancer," said Dr. Stephen B. Gruber of the University of Michigan's Comprehensive Cancer Center. "They are different diseases with different genetic factors."

Other Sources: Journal of the National Cancer Institute