ANN ARBOR, MI - An international research team studying Israeli colon cancer patients has identified a new virulent genetic risk factor that can lead to early screening methods to save the lives of people who have this genetic disposition for colon cancer.

The team, led by Stephen B. Gruber, M.D., Ph.D., of the University of Michigan Health System and Steven Lipkin, M.D., of the Chao Comprehensive Cancer Center at the University of California , Irvine , discovered a novel mutant gene that significantly increases the risk of colon cancer.

The researchers found that people with this genetic variant form of MLH1, a gene already linked with colon cancer, have a 40 percent lifetime risk of getting colon cancer, as compared to a 6 percent risk for the general population. Study results appear as an advance online publication on the Web site of Nature Genetic.

Colorectal, or colon, cancer is one of the most common forms of cancer in the United States. The National Cancer Institute estimates that some 150,000 new cases will be diagnosed in 2004, and more than 55,000 deaths from colorectal cancer will occur. Some one-quarter of all patients have a family history of colorectal cancer that suggests a genetic contribution. It is preventable though early detection.

Colorectal cancer rates in Israel are among the highest in the world. Over the past three years, the research team has been conducting a genetic epidemiological survey of colon cancer patients in northern Israel and found that more than 1 percent carried this previously unidentified variant gene, called MLH1 D132H. Significantly, these patients were found to have no other risk factors, and they could not be identified with one particular ethnic, cultural or religious group.

“Because this genetic change is found in colon cancer cases from all major ethnic groups in Israel , it's likely that the genetic change also plays a role in colorectal cancer in other populations,” says Laura Rozek, Ph.D., a post-doctoral research fellow at UMHS who led the study's analytic effort. “People with this genetic change are five times more likely to develop colorectal cancer than the general population.”

Gruber, who directs the UMHS Cancer Genetics Clinic, notes that this discovery could be important to patients with familial forms of colorectal cancer. “People who carry this genetic variant are likely to benefit from screening with colonoscopy, and we already know that colonoscopy saves lives,” Gruber says.

Along with Lipkin, Gruber and Rozek, Jessica Peng-Chic and Brian Shin of UCI, Joel K. Greenson and Eric Fearon of UMHS; Gadi Rennert of the Carmel Medical Center and Technion Faculty of Medicine in Haifa, Israel; Wei Yang of the National Institute of Diabetes and Digestive Kidney Diseases in Bethesda, Md.; Joseph Hacia and Nathan Hunt of the University of Southern California in Los Angeles; Mark Kokoris of BioCaptus in Bothell, Wash.; Henry Lynch of Creighton University in Omaha, Neb.; Francis Collins of the National Human Genome Research Institute in Bethesda; and Steve Fodor of Affymetrix Corp. in Santa Clara, Calif., participated in the study. The American Cancer Society, Ravitz Foundation, and National Institutes of Health provided funding.

Contact: UMHS: Nicole Fawcett or
UCI: Tom Vasich, tmvasich@uci.edu , 949-824-6455

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