NEW YORK (Reuters Health), Jul 25 - Most expert panels have recommended that colonoscopy be repeated every 10 years after an initial negative result. However, researchers in Germany now report that the risk of colorectal cancer following an initial negative screening colonoscopy is quite low and it need not be repeated for at least 20 years "if at all."
To determine the risk of colorectal cancer occurrence after a colonoscopy negative for polyps or cancer, Dr. Hermann Brenner, from the German Cancer Research Centre in Heidelberg, and his colleagues conducted a population based case-control study.
They selected 380 cases of primary invasive colorectal cancer, detected because of symptoms, fecal occult blood testing results, or other indications, rather than by screening, among subjects age 30 or older between January 2003 and June 2004, in a region in southwest Germany. Most of the subjects were middle-aged. These patients were matched to 485 community-based, randomly chosen control subjects by age, gender, and county of residence.
The subjects were interviewed about previous endoscopic screening of the large bowel, and their reports were validated by review of their medical records. The authors excluded patients whose cancer was detected by screening or who had a history of inflammatory bowel disease.
The researchers determined risk after adjusting for potential confounders -- education, family history, smoking, use of NSAIDs, hormone replacement therapy, BMI, and participation in a general health screening examination.
Their results, reported in the August issue of Gut, show that 27.6% of controls and 7.9% of cases had ever had a previous colonoscopy negative for polyps or cancer. A previous negative colonoscopy was associated with a reduced risk of colorectal cancer (adjusted odds ratio 0.26), Dr. Brenner and his associates report.
The decreased risk persisted throughout 20 years, and was even lower among subjects who had a negative colonoscopy at age 55 or older, suggesting that among subjects in this older age group, "a very low risk might prevail throughout their remaining life expectancy." The research team believes this reflects "the very slow development of colorectal cancer from precancerous lesions."
Dr. Brenner and his colleagues suggest that increasing the time interval between colonoscopies would increase the screening's cost-effectiveness and reduce the risk of complications.
Moreover, "colonoscopy-based screening may become feasible even in countries with limited resources for high quality colonoscopy."
Last Updated: 2006-07-25 11:20:26 -0400 (Reuters Health)
Gut 2006;55:1145-1150.
Related Reading
Extracolonic findings double VC costs, but might be worth paying, July 20, 2006
Copyright © 2006 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
