Colorectal cancer is the second leading cause of death from cancer in the United States. The American Cancer Society's current guidelines for colorectal cancer screening include examination of the sigmoid portion of the colon every 5 years and colonoscopy every ten years. However, the appropriate interval for re-screening after a negative colonoscopy is uncertain. A re-screening interval of 5 years or longer after a normal colonoscopy is appropriate, according to a new study published in The New England Journal of Medicine .

Researchers from the Indiana University School of Medicine and their colleagues studied 1256 people with an average age of almost 57 years who were determined to have an average risk of colorectal cancer. These individuals had no adenomas, or benign tumors, at a baseline screening colonoscopy. At follow-up colonoscopy 5 years later, none of these individuals were found to have colorectal cancer. Approximately 16% of the study participants had adenomas and only 16 of them had advanced adenomas.

From this information, the researchers concluded that the five-year risk of colorectal cancer is extremely low among people with a normal screening colonoscopy. It's not clear how these results affect the current ten-year screening interval, but it seems that a screening interval of 5 years or longer may be appropriate for people with an average risk of colorectal cancer and a negative initial colonoscopy.

Source

N Engl J Med. 2008;359:1218-1224.