Colon Cancer Screening: Any Test Better Than No Test at All

From the WebMD Archives

Nov. 29, 2000 -- When his stomach problems first started several years ago, Edward Leigh's family doctor chalked it up to stress. By the time his colon cancer -- or colorectal cancer -- was finally diagnosed in August 1999, Leigh, 42, was experiencing regular bouts of severe bleeding. His symptoms were attributed, at various times, to irritable bowel syndrome, food poisoning, and hemorrhoids.

"Even with all my symptoms, I never thought of colon cancer," Leigh tells WebMD. "When I first started having symptoms, there just wasn't any public awareness about colon cancer. It wasn't that I denied the possibility of cancer, it just never crossed my mind."

Because of the delay in getting diagnosed, Leigh's cancer was found at an advanced stage and required aggressive chemotherapy. The motivational speaker now devotes much of his time to raising public awareness about colon cancer, and urging people to get tested -- early and often.

Now a long-term follow-up study from the University of Minnesota in Minneapolis suggests that the simplest and cheapest test available for detecting colon cancer can actually prevent the disease. Moreover, experts are using the findings to try to shift the public focus from the debate over which screening tool to use and how often, to getting screened early and often, no matter what method is used.

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Writing in the Nov. 30, 2000 issue of The New England Journal of Medicine, researchers involved in the Minnesota Colon Cancer Control Study reported a 20% reduction in the incidence of colon cancer among those with no symptoms who received either yearly or twice yearly fecal occult-blood screenings. The study included over 46,000 people between the ages of 50 and 80 who were followed for 18 years.

Fecal occult-blood screening is a stool test that looks for microscopic amounts of blood too small to be seen with the naked eye. The advantage of the test is that it is much cheaper and less invasive than other testing methods like flexible sigmoidoscopy and colonoscopy. The disadvantage of the test is that it is not very accurate. Blood in the stool could be due to many factors, including ulcers and hemorrhoids. And because many tumors do not bleed, negative results are possible in people that actually have cancer.

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The findings confirm the long held belief that identifying and removing the polyps known to often lead to colon cancer actually prevents the disease. In the study, all patients with abnormal fecal occult blood tests were advised to undergo more extensive testing and have all detected polyps removed.

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"For the first time, we are able to show that this screening procedure for colorectal cancer not only reduces [the death rate], but also reduces the incidence of the disease," lead researcher Jack S. Mandel, PhD, of the scientific consulting firm Exponent in Menlo Park, Calif., tells WebMD. "We have shown that routine screening of [people without symptoms] at average risk for colon cancer significantly reduces incidence."

Colon cancer is the second-leading cause of cancer death in the U.S., with about 160,000 new cases diagnosed each year and 56,000 deaths attributable to the disease. The goal of screening is to detect and remove polyps before they turn into cancer, so regular testing is critical for those at high risk.

Fecal occult blood testing is one of several tests routinely used to screen for colon cancer, and there is much controversy regarding which test or combination of tests is best for people who have no symptoms.

The American Cancer Society and most other advocacy groups recommend fecal occult blood testing for everyone over the age of 50, but roughly 70% of people in this age group in the U.S. have never had any kind of colon cancer screening.

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Flexible sigmoidoscopy, in which a flexible tube with a light and camera on the end probes the lower third of the colon, is also recommended every five years. Colonoscopy is widely recognized as the most accurate test available, but it is also the most expensive and requires sedation.

Despite mounting evidence that screening for colon cancer saves lives, many doctors are still reluctant to recommend the procedures to their patients, says Steven H. Woolf, MD a professor of family practice at Virginia Commonwealth University.

"While we debate among ourselves about which test is best, most people aren't being tested at all," Woolf tells WebMD. "My philosophy with my own patients is that if I can get them to get screened with any one of these tests, I am happy. I think there is a move toward shared decision-making in general, because patients are more empowered than they were even a few years ago. They come in with more information." Woolf wrote an editorial that accompanies the study.

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Researcher Ernest Hawk, MD, of the National Cancer Institute, agrees. The biggest factor in reducing deaths from colon cancer is not which test a patient has, he says, but getting patients to be tested at all. Hawk is chief of the Gastrointestinal and Other Cancers Research Group for the Institute's Division of Cancer Prevention.

"Each of these tests has limitations and benefits. Because this decision is so complex, it probably should be left to those being tested," he tells WebMD. "There is no question that doing something with regard to testing is better than doing nothing. Everyone who is older than 50 should undergo some form of colorectal cancer screening."

Edward Leigh believes that routine testing should begin at age 40 with a colonoscopy to start with, and he points out that 10% of colon cancers in the U.S. are diagnosed in those under the age of 50. He adds those with symptoms should be checked for the disease immediately -- no matter what their age.

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"My primary care physician lacked an understanding about colon cancer, but even those who do know about the disease often don't think about it when a younger person presents with symptoms," he says.

Hawk says new techniques may soon make the testing decision much less complicated for both patients and doctors. He points to a preliminary study, published recently by researchers at the Mayo Clinic in Rochester, Minn., showing that DNA abnormalities specific to colon cancer can be measured through stool testing -- an indication that DNA testing may one day be an options. More studies of the technique are underway.

"If this turns out to be an accurate test to identify cancer and polyps through a stool-based method, it should greatly improve compliance," Hawk says. "Stool based tests are in many ways more attractive than endoscopic tests."

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