Less Invasive Cancer Screen May Save Lives
Early results good on sigmoidoscopy for colorectal polyps
TUESDAY, Dec. 3, 2002 (HealthDayNews) -- A less demanding method of looking at the intestines than the currently recommended technique might be a more practical way to screen for the early, preventable signs of colorectal cancer, an Italian study suggests.
Early results from a trial that includes more than 34,000 adults indicate that a single examination using sigmoidoscopy "can be an acceptable and safe screening strategy for colorectal cancer," says a report in tomorrow's issue of the Journal of the National Cancer Institute.
The idea is to detect polyps, abnormal growths that can be removed before they develop into cancer. The American Cancer Society now says the ideal screening program would have every adult undergo an examination called a colonoscopy at the age of 60, and preferably every 10 years after that. It recommends a sigmoidoscopy every five years, preferably accompanied by a test for bleeding caused by polyps.
However, a colonoscopy is not easily done. It requires a dietary preparations starting the day before, an enema taken in the evening to clear out the intestine and nothing but clear fluids before the examination, which usually requires sedation. A physician can then insert a lighted, flexible tube that allows the entire intestine to be examined for polyps.
Sigmoidoscopy is much less demanding because it uses a shorter tube that inspects only part of the intestine. The Italian study's potential advantage is that the relative ease of having a sigmoidoscopy will lead many more people to have a screening test and thus save lives even though the examination does not detect as many precancerous growths.
"This strategy is expected to reduce the risk of colorectal cancer by 40 to 50 percent, which is less than would be achieved by colonoscopy," says Dr. Nereo Segnan, a lecturer in epidemiology at the University of Turin and leader of the study group. "We hope to show that this strategy is adaptable for use in large populations."
The journal paper is a preliminary report on the study. Among those participants who had sigmoidoscopies -- half did not -- the number who were found to have polyps (10.8 percent) and who had cancers (5.4 percent) were in line with predictions based on overall incidence of the condition. Tellingly, more than 80 percent of those who had the examination said the pain was as mild or milder than they expected.
It is still too early to draw any conclusions, Segnan says, because the study has another three years or more to run. Only if the final results show a significant reduction in cancer illness and deaths will it be possible to recommend any change in screening strategy, he says.
"On the other hand, there is a lot of observational information on the effectiveness of sigmoidoscopy in reducing the incidence and mortality of colorectal cancer," Segnan says.
The Italian study is being watched closely, says Dr. Durado Brooks, director of colorectal cancer for the American Cancer Society. It is the second most common form of cancer in the United States, with 148,300 new cases and 56,600 deaths expected this year.
"The idea that one-time screening at 55 or 60 using sigmoidoscopy might be sufficient is not a new concept," Brooks says. "This is the largest study ever to look at it."
One encouraging finding is that more than half the cancers detected in the study were found at the earliest, most treatable stage, when the survival rate is about 90 percent, he says. Only 37 percent of the cancers detected in colorectal screening programs in the United States are at that early stage, Brooks says.
"But it will be important to see whether there will actually be a large number of people dying of cancers that are out of the reach of sigmoidoscopy," he says. "Sigmoidoscopy is a useful screening test. Whether it is optimal remains to be seen."
What To Do
A guide to colorectal cancer, its symptoms, screening tests and treatment, can be found at the American Cancer Society. Meanwhile, the National Institute of Diabetes and Digestive and Kidney Diseases explains a sigmoidoscopy.