Guidelines on colon cancer screening pegged for update
■ Researchers suggest refinements to reflect gender differences on neoplasia findings, as well as new technologies.
By Susan J. Landers — Posted Dec. 4, 2006
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Washington -- A new study delineating possible revisions in colorectal cancer screening guidelines likely will attract the attention of physicians from an across-the-specialty spectrum who are engaged in debate and discussion in preparation for next year's release of updated recommendations.
Gastroenterologists, radiologists, surgeons, primary care physicians and others have joined forces as the U.S. Multisociety Task Force on Colorectal Cancer and are considering new data and new technologies in updates to their 1997 guidelines, which were last modified in 2003.
Meanwhile, the U.S. Preventive Services Task Force plans to review its 2002 guidelines and could publish a new version next year that reflects changes in the field.
The study, "Colonoscopy in Colorectal-Cancer Screening for Detection of Advanced Neoplasia," which appeared in the Nov. 2 New England Journal of Medicine, could provide key talking points as efforts move forward. Conducted in Poland, the study analyzed data from a screening program of more than 50,000 participants. Researchers concluded that men had a considerably higher risk than women of harboring advanced neoplasia. This finding led them to suggest that screening requirements be revised to reflect this difference.
Currently men and women at average risk are urged to begin having screenings at age 50.
Colon cancer is the most frequently detected cancer in Europe and the second leading cause of cancer deaths in the United States, said the study's authors. The Centers for Disease Control and Prevention reports that 28,471 men and 28,132 women in the nation died of the cancer in 2002.
If everyone age 50 and older had regular screening tests, at least one-third of the deaths could be avoided, the CDC predicts.
That colon cancer is a major killer in Poland was a driving factor behind the study, said Dr. Jaroslaw Regula, the study's lead author and a physician in the gastroenterology department at the Maria Skodowska-Curie Memorial Cancer Center in Warsaw. The researchers coupled this information with the knowledge that colonoscopy is emerging as a gold standard screening technique for detecting precancerous lesions.
"It was our initial intention to find subgroups that have the highest benefit from screening to increase its effectiveness. Because the lifetime risk of colorectal cancer is similar for men and women, it is a bit surprising to find that advanced neoplasia can be found in a greater proportion of men than of women," he said. "Our study may suggest that screening in men should start earlier than at age 50 years."
Weighing risk factors
Experts contacted about Dr. Regula's study cautioned that it may be premature to consider changes in guidelines along male-versus-female lines. Although gender could be a consideration in new recommendations, it would be included for more complex reasons and as just one of many factors, such as family history.
"It's been appreciated for a long time that men are slightly more susceptible to developing colorectal cancer," said Durado Brooks, MD, MPH, the American Cancer Society's director of prostate and colorectal cancers. "The problem is that women, and maybe the public in general, have viewed it as a man's disease, and that's just not at all accurate."
"At any particular point in time, men have a higher proportion of cancers due to their gender," said Bernard Levin, MD, vice president of cancer prevention at the University of Texas M.D. Anderson Cancer Center in Houston. "But it's over a lifetime that men and women come close to having the same incidence rate of colon cancer, because women live longer."
What's missing from the study is information on where in the colon the lesions were found, Dr. Brooks said. But Dr. Regula said those data will be published in a future article.
Tumor location is important because current evidence suggests that women are more likely to have lesions in a part of the colon that can be reached only by colonoscopy. Lesions in men are frequently found in the distal part of the colon, which can be reached with flexible sigmoidoscopy.
This finding has led to thoughts that different kinds of tests could be recommended for men and women, Dr. Brooks said.
"We continue to debate whether we should offer screening differently for women and men, or should we offer a different mix of screenings depending on age," said Sidney J. Winawer, MD, a gastroenterologist at Memorial Sloan-Kettering Cancer Center in New York City and an author of the multisociety task force's 1997 guidelines. For example, perhaps fecal occult blood testing could be offered early, saving the colonoscopy for later -- a practice common in Germany, Dr. Winawer said.
"We are looking at all the currently available technologies including FOBT, flexible sigmoidoscopy, colonoscopy and double-contrast barium enema," said Dr. Levin, who co-chairs the multisociety task force's guidelines efforts.
Dr. Levin also provided a glimpse of the technologies that are not quite ready for prime time but are factors in the group's discussions. Virtual colonoscopy, also called computed tomographic colonography, and stool DNA testing are among them. Capsule endoscopy already is in use to examine the lining of the gastrointestinal tract, and the Aer-O-Scope, in development in Israel, is billed by its manufacturer as a miniaturized, self-propelling, self-navigating colonoscopy. Dr. Levin serves on that company's scientific board.
"But don't wait," for a noninvasive yet comprehensive exam, he advises. "We have great technology already."