Colonoscopy can reduce overall risk of colorectal cancer by 70%

Using colonoscopy to screen average-risk people can reduce the overall risk of a late-stage colorectal cancer diagnosis by about 70 percent, according to a new study.

Researchers analyzed the health records of 1,012 average-risk adults ages 55 to 85 to determine the effect of screening colonoscopy or sigmoidoscopy on the risk of being diagnosed with late-stage colorectal cancer. In addition to the 70 percent reduction in overall risk, people who had been screened using colonoscopy had a 74 percent reduction in risk for left-sided colorectal cancer and a 64 percent reduction in risk for right-sided colorectal cancer. (The right side of the colon, also known as the ascending colon, travels up the right side of the abdomen. The left side, or descending colon, travels down the left side of the abdomen.)

By contrast, people who had been screened with sigmoidoscopy had a 50 percent reduction in overall risk for late-stage colorectal cancer, a 64 percent reduction in risk for left-sided colorectal cancer and a modest 21 percent reduction in risk for right-sided colon cancer.
Among the 474 people in the study who had advanced colorectal cancer, 251 (53 percent) had advanced cancer on the right side of the colon, which likely would not have been detected by sigmoidoscopy.

Colonoscopy has been widely recommended as a screening tool for colorectal cancer since it allows a physician to detect and remove polyps that might turn into cancer, and find early-stage cancers that are more likely to respond to treatment. However, the tests ability to detect right-sided colorectal cancer has been questioned, said study leader Dr. Chyke Doubeni, presidential associate professor of family medicine and community health at the Perelman School of Medicine at the University of Pennsylvania....

Suggestions for lifestyle modifications include: maintaining a healthy body weight and exercising to reduce the risk of obesity. A reduction of dietary fat to less than 30% of caloric consumption and an increased intake of fresh fruit and vegetables, with at least 25 grams of fiber and protective omega-3 fats common in fatty fish, nuts and canola oil can be helpful.

A new study from the the Dana-Farber Cancer Institute in Boston showed that the heavier a person is and the less exercise he or she does, the greater the likelihood of developing a specific type of colorectal cancer. By contrast, the more physical activity a person did, the lower the risk for CTNNB1-negative colon cancer. Study participants did aerobic activities such as walking (at a usual pace), jogging, running, bicycling, swimming laps, playing racquet sports and lower-intensity activities such as yoga, toning and stretching....