The U.S. Preventive Services Task Force has rejected the latest X-ray screening technology, called CT colonography, saying that more research is needed. The government task force also said everyone ages 50 to 75 should get screened with one of the tests: a colonoscopy for the entire colon every 10 years, a sigmoidoscopy of the lower colon every five years, combined with a stool blood test every three years and a stool blood test every year.

But people over 75 who have screened negatively and have no signs of the disease should stop getting routine colon cancer tests. The panel said that after the age of 75, the risk of the procedure outweighs the benefits for most patients. The risks of colonoscopy can include infection, perforated colon and reaction to sedatives.

Screening for polyps is recommended at age 50, but people avoid standard procedures because they are unpleasant. They involve inserting a long and flexible tube in a patient’s large intestine (rectum and colon). A small video camera is attached to the colonoscope so that your doctor can take pictures or video of the large colon. The test helps find ulcers, polyps, tumors and areas of inflammation or bleeding.

The virtual version of the test is done mainly outside the body and uses an X-ray computed tomography or CT scanner. A recent report published in the New England Journal of Medicine found that the technique was able to detect 90% of precancerous polyps 10 millimetres or larger.

Colon cancer is the second-leading cause of cancer death in the United States and the third most common cancer in Canada behind breast and lung cancer in women and prostate and lung cancer in men.

Cancer of the colon and rectum (also called colorectal cancer) includes cancerous growths in the colon, rectum and appendix. The spread of colon cancer to distant organs is called metastasis of the colon cancer. The disease causes 655,000 deaths worldwide per year. It is common in the Western world and is rare in Asia and Africa.