Work done by researchers at Memorial University has contributed to the identification of a genetic variation on chromosome 8 associated with increased risk of colorectal cancer. This work may help lead to screening tests for people at risk for the disease.
The discovery was published July 9 online in Nature Genetics in a paper by scientists at research institutions in Ontario, Quebec, Newfoundland and Labrador, the U.K., France and the U.S. Two other papers in the same online publication from researchers in the U.K. and in the U.S. also independently show that a region on chromosome 8 is linked to colorectal cancer.
At Memorial University, Drs. Jane Green, Roger Green, Patrick Parfrey, Mike Woods and Ban Younghusband were among those involved in the Canadian study. About 800 people from Newfoundland were part of the study population.
“We have a long history of research on colon cancer in Newfoundland and in 1993 the first major gene for high risk of colon cancer was identified through studying a Newfoundland family,” said Dr. Jane Green, Discipline of Genetics. “In some very high-risk families we have identified a specific mutation and there is now a genetic test. What is important about the new findings is that we have identified a genetic region for people with an intermediate risk of colon cancer. This doesn’t mean there will soon be a specific test for this group but with more work we can probably develop a panel of tests that can identify those at a higher-than-average risk.”
Colorectal cancer is the second deadliest form of cancer in Canada, and the rate of colorectal cancer in the country is highest in Newfoundland and Labrador. Caught early, this cancer can be treated and cured. However most cases are found too late when the cancer has spread so treatment is unsuccessful. If people know they are at risk, screening can identify early signs of the disease and potentially cancerous polyps can be removed.
“Because the rate of colon cancer is so high in this province it is particularly important that we have an understanding of who is at risk so we can provide screening and early diagnosis and treatment,” said Dr. Green.
While many cases of colon cancer are triggered by environmental or unknown factors, it is estimated that at least 30 per cent of cases are associated with a familial link. The genetic marker on chromosome 8 appears to increase a person's risk of colon cancer by about 20 per cent.
Dr. Green said it is probable that other genes are involved in the disease but this is the first genetic predictor in a decade. Work will continue to identify further genetic predictors and use them as a combined predictive tool to find out who is at increased risk for colon cancer and who should be screened at an early age.