Risk of colorectal cancer extremely low 5 years after a normal colonoscopy screening

A study appearing in the Sept. 18 issue of the New England Journal of Medicine shows that among individuals with no colorectal neoplasia (abnormal growths) on initial screening colonoscopy, the five-year risk of colorectal cancer is extremely low. The data provides support for rescreening at an interval of five years or longer after a normal colonoscopic examination. "This research is very significant as it is the first large study to provide direct rescreening data on a group of average risk patients who had normal findings on the initial screening colonoscopy," said John L. Petrini, MD, FASGE, president, American Society for Gastrointestinal Endoscopy (ASGE). "As a result, physicians should consider this important finding when recommending a rescreening schedule to their patients, as this data could have an impact on the costs of colonoscopy and the resources to provide for colonoscopy. There is data suggesting that the procedure may be performed too frequently."

Researchers, led by Thomas F. Imperiale, MD, of the Indiana University School of Medicine and the Regenstrief Institute, examined 1,256 asymptomatic patients 50 years or older, who had no precancerous or cancerous findings on baseline colonoscopy and who underwent follow up colonoscopy at five years. Among this patient population, no cancers were discovered. Advanced adenomas were found in 16 patients (1.3 percent).

ASGE and American Cancer Society colorectal cancer screening guidelines for patients with normal findings on the initial screening colonoscopy recommend repeat screening for average risk individuals every 10 years if they have no symptoms or family history risk. While this data does not directly evaluate the 10-year recommendation, it does establish that colonoscopy screening does not need to be repeated before five years for average risk individuals.

An estimated 49,960 deaths are expected to occur from colorectal cancer in 2008. According to a study released in October 2007 from the CDC and the American Cancer Society, colorectal cancer deaths dropped nearly 5 percent between 2002 and 2004, more than the other major cancer killers (prostate, breast, and lung). Among the key factors playing a role in the decline was prevention through screening and the removal of precancerous polyps.

"This is excellent news and reinforces the importance of colorectal cancer screening beginning at age 50, or even younger if there is a family history of colorectal cancer or polyps," said Petrini. "Colonoscopy plays a very important role in colorectal cancer screening and prevention because it is the only method that allows us to remove polyps before they turn into cancer."

Source: American Society for Gastrointestinal Endoscopy