The flexible sigmoidoscopy is similar to a colonoscopy but looks only at the rectum and about one-third of the colon. A double-contrast barium enema expands the colon and then takes X-ray pictures. The virtual colonoscopy takes X-ray pictures as it rotates around the body.
“A menu of tests exists, but the colonoscopy is by far the best and most powerful,” says March Seabrook, M.D. a gastroenterologist and Governor of the American College of Gastroenterology in South Carolina. “The colonoscopy will see polyps that are as small as one millimeter—those would never be detected by the other tests. Plus, other tests do not allow you to remove an abnormal growth,” he says.
Tests to primarily detect cancer
The second set of tests—primarily to detect cancer, not polyps—includes the guaiac-based fecal occult blood test, fecal immunochemical test, and stool DNA test. These tests require collection of stool (feces) samples.
However, “Fecal tests are cancer detectors and that is not what we are after. The goal of colorectal cancer testing is cancer prevention,” says Seabrook.
If a stool test shows abnormal results, a colonoscopy is then recommended to get a closer look. “The problem with stool tests is there are so many false positives. That means you will have to have a follow-up colonoscopy anyway,” says Stuart Lichtman, M.D., F.A.C.P., associate attending physician at Memorial-Sloan Kettering Cancer Center.
Look at your own risk
Screening for colorectal cancer should start at age 50. But “If you have had colon cancer or polyps, let your children know because they should start screening earlier at age 40,” Samuelson says.
Several factors can put you at higher risk for colorectal cancer. According to the American Cancer Society, the links between diet, weight, and exercise and colorectal cancer risk are some of the strongest for any type of cancer (see sidebar on preventive lifestyle activity).
People with type 2 (usually non-insulin dependent) diabetes have an increased risk of developing colorectal cancer as well as people with inflammatory bowel disease, which includes ulcerative colitis and Crohn’s disease.
Pass the test
Lichtman encourages older adults to get the colonoscopy. “By doing it, you may prevent having cancer five years from now. If someone could not be cleared for surgery, I weigh the risk of a colonoscopy. But if someone could be cleared for surgery, I tell them they should have a colonoscopy,” Lichtman says. “I always tell people ‘I don’t want to give you chemotherapy. Please get a colonoscopy.’”
“We don’t know how to prevent breast cancer or prostate cancer, but we do know how to prevent colorectal cancer. Everyone 50 and above should have their colon examined . . . If you have a clean colonoscopy in your 70s, the likelihood of developing colorectal cancer after that is low,” says Seabrook.
Keep your colon healthy
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■ Eat a low-fat diet and 25-30 grams of fiber a day
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■ Eat five or more fruits and vegetables each day
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■ Choose whole grain foods like whole grain bread, whole grain pasta, brown rice, and corn
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■ Limit the amount of processed meats and red meats you eat
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■ Drink no more than two alcoholic drinks a day for men and one for women
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■ Maintain a healthy weight
■■ Exercise at least 20–30 minutes at least three days a week