Scientists reported discovery of a gene suspected of playing a key role in colon cancer's earliest stages, a finding that may lead to better ways of detecting and treating America's No. 2 cancer killer.

A team of U.S., British and Japanese scientists, including a University of Utah researcher, Ray White, who is a professor and co-chairman of the Department of Human Genetics, reported Thursday that it has pinpointed a gene on the long arm of chromosome 5 that appears to be flawed in certain colon tumors.All humans have 23 pairs of chromosomes which carry genes, the inherited blueprints for everything from hair color to the risk for developing certain diseases.

Three other genes already have been linked to colon cancer. But the newly discovered mutation, thought to remove a natural brake on cell growth, appears to occur earlier than the other defects in the pathway leading from normal cell growth to cancer's devastating, runaway growth, scientists said.

The team, headed by Dr. Bert Vogelstein of Johns Hopkins University School of Medicine in Baltimore, zeroed in on the so-called long arm of chromosome 5 after its previous work found people with an inherited tendency to colon cancer shared an unique genetic pattern in that area. The region was also known to be a frequent target of genetic damage in colon tumors in people without a strong family history of the disease.