Colon Cancer Test -- Once May Be Enough
Single Test May Be More Acceptable to Patients
Dec. 3, 2002 -- Colorectal cancer is highly curable when detected early, but the thought of having a tube inserted into the rectum -- and going back regularly for more -- scares many people away. Now, preliminary results from a new study suggest a less aggressive approach can save lives.
The ongoing study is being conducted to assess the impact of a single screening -- with a test called a sigmoidoscopy. Lead researcher Nereo Segnan, MD, tells WebMD that one-time screening around age 60 is less costly and more acceptable to patients than routine screenings every few years.
Flexible sigmoidoscopy involves the insertion of a hollow, lighted tube into the rectum to inspect the lower third of the colon for suspicious growths or precancerous polyps. Roughly 70% of cancers are found in this area, and the test often identifies abnormalities associated with tumors that are higher up.
Segnan and colleagues from Turin, Italy's Cancer Prevention Center screened approximately 17,000 people between the ages of 55 and 64 with flexible sigmoidoscopy. A similar number of participants received no screening. The findings are published in the Dec. 4 issue of the Journal of the National Cancer Institute.
Screening was found to be effective in identifying suspicious polyps and patients who needed further testing with colonoscopy -- a test similar to sigmoidoscopy that allows viewing of the entire colon.
Fifty-four cancers were identified, and more than half involved highly treatable, early-stage malignancies. Four out of five people described the pain associated with screening to be mild or less than expected. Since the single test found a large number of advanced abnormalities and early cancers, the researchers conclude that this strategy could make a large impact on colorectal cancer frequency and deaths.
Segnan concedes that colonoscopy is more effective than sigmoidoscopy. But because it is much more expensive and typically involves sedation, many people are unable or unwilling to have it.
"I think the best screening test for colorectal cancer is the test that gets done," Segnan says. "Because one-time sigmoidoscopy is cheaper and better accepted, more people will get screened and screening will have more impact on cancer [frequency] and deaths."
Leading colorectal cancer experts contacted by WebMD agree that making screening acceptable to a wider number of people is critical to saving lives. They say that the single-test approach has merit, but it is too soon to say whether one-time screening is effective.
"Our message is that any test you have is better than not being tested at all," says Durado Brooks, MD, MPH, director of colorectal cancer research for the American Cancer Society. "Right now the screening rate in this country is around 40% and our early-stage diagnosis is only about 37%. The benefits of any colorectal cancer screening are huge, and it is a crime that it is underutilized."