Colorectal cancer deaths and colonoscopy
Research in Canada to check the benefits of colonoscopy in preventing deaths from colon cancer have shown that it does have a positive effect in reducing risk of death but only significantly when the tumour is in the left side of the colon. This is thought to be because the right hand side is harder to get to and see effectively with the colonoscope.
Cancer of the rectum and the colon is the second most common cancer in North America. Colonoscopy - the viewing of the inside of the colon via a long, flexible tube inserted into the rectum, is generally advocated as the preferred screening method for colon cancer and it can help prevent about two-thirds of deaths due to this cancer. But there are no randomized trials to support its benefit.
The large bowel extends from the rectum up the left side of the abdomen, across, and down the right side to the caecum, or junction with the small intestine. Although the entire colon should be inspected during a colonoscopy, the caecum and the right side of the colon can be difficult to reach during insertion of the colonoscope.