Jefferson Researchers Develop New Model To Gauge Risk of Inherited Colon Cancer

Jefferson cancer researchers have devised a model using age at colon cancer diagnosis to determine a person's risk for an hereditary form of the disease that often develops before age 55.

The research finding is directed at detecting risk for hereditary non-polyposis colorectal cancer (HNPCC), which accounts for about 5 percent of all colorectal cancers.

The new model applies to all people diagnosed with colon cancer. These patients may have either hereditary or non-hereditary forms of colon cancer.

The purpose of the model is twofold. The first is to gauge the risk that the diagnosed colon cancer patient may actually have HNPCC. Its second purpose is to warn family members that they may have inherited the same disease and so should be screened to prevent cancer.

The model offers particular hope for identifying risk in colon cancer patients who don't have a family history of cancer that can serve as a sign of a hereditary cancer trait.

The research team leader is Bruce M. Boman, MD, PhD, the Robert L. Capizzi Professor of Medicine, Jefferson Medical College (JMC), and Director of the Division of Medical Oncology and Medical Genetics, Department of Medicine, JMC.

"This is one of the first epidemiological models, as far as I know, to determine risk for hereditary colorectal cancer," says Dr. Boman, who is also Director of the Gastrointestinal Cancer Program of the Kimmel Cancer Center at Jefferson.

"Since we know that patients develop HNPCC at an early age, we compared the age at diagnosis of colon cancer patients with HNPCC against all colon cancer patients. We used differences between these two groups of patients as basis for the model."

The model indicates that individuals diagnosed with colon cancer before age 35 have a very high risk — a 39 percent chance — of carrying the HNPCC trait when family history of cancer is negative. For those 55 years or older, the risk drops to less than 10 percent.

Genetic Testing Important

The research team's analysis stresses the importance of genetic testing for HNPCC in all patients diagnosed with colon cancer before age 55.

Dr. Boman believes that the model will be particularly valuable for genetic counselors who do risk assessment of patients with colon cancer. It will provide the percentage risk and will also provide an "age" criterion for ordering genetic tests.

"The model has the potential for saving lives because it may allow us to find out who else in the family is at risk before that family member develops cancer," he says.

Dr. Boman presented his work at the 50th annual meeting of the American Society of Human Genetics in Philadelphia.