Two OICR scientists have uncovered the first genetic predictor for the most common forms of colorectal cancer, which could someday lead to a blood test to be used as part of a comprehensive screening program.

Dr. Tom Hudson, OICR’s President and Scientific Director, and Dr. Brent Zanke, Vice-President OICR and Director, Ontario Tumour Bank, were co-leaders of the Assessment of Risk for Colorectal Tumours in Canada (ARCTIC) project. Their project team included co-investigators from the U.S., France, England and Scotland.

The study, published in July in the journal Nature Genetics, analyzed 100,000 samples from 10,000 people, including 2,400 Ontarians in the Ontario Familial Colorectal Cancer Registry.

“Ontario has one of the highest rates of colorectal cancer in the world, so it is important for us to take a leading role in research in this area, where we are also fortunate to have considerable expertise,” explains Dr. Hudson. “Ontario also has a low level of screening for colorectal cancer, so naturally we are looking at ways to improve the screening process through research.”

The ARCTIC project identified a specific genetic variation on chromosome 8 that is associated with colorectal cancer. Chromosome 8 has been previously linked to other forms of cancer, including that of the prostate, meaning the newly discovered variation could suggest risk for a broad spectrum of cancers.

Cancer Care Ontario, the Government of Ontario agency charged with delivering cancer care and prevention and a partner in the ARCTIC study, estimates that 7,800 Ontario residents will be diagnosed with colorectal cancer in 2007. More than 3,200 will die from the disease.

One of the major factors in determining whether a patient will survive the disease is the stage at which tumours are detected. Zanke believes that making the screening process more individualized could lead to earlier detection and also cost-savings.

"This breakthrough could lead to new methods of testing for colorectal cancer," said Dr. Brent Zanke, co-principal investigator and scientist at Cancer Care Ontario. "For example, this genetic variation could be detected through a tool as simple as a blood test. Used with other tools as part of a screening program, this information could help individualize screening and prevention efforts saving lives and money."

Hudson says he would like to see screening become a regular part of all older Ontarians’ health care.

“Right now, only 17 per cent of Ontarians over 50 get a fecal occult blood test, and we don’t know whether we’re screening the people who are most at risk. If we could screen all older adults with a quick blood test then refer those who are at elevated risk for further testing, we could catch tumours sooner and ultimately save more lives."