Study leader Dr. Thomas F. Imperiale of the Indiana University School of Medicine and the Regenstrief Institute in Indianapolis 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, Imperiale said.

"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," Dr. John L. Petrini, president of the American Society for Gastrointestinal Endoscopy said in a statement. "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."

The study is published in the New England Journal of Medicine.