Only fecal occult blood testing, sigmoidoscopy, or colonoscopy is recommended, starting at age 50.
The U.S. Preventive Services Task Force (USPSTF) has been releasing new and updated guidelines periodically. The USPSTF grades each of its recommendations according to a system described on the USPSTF website.
In 1996, the USPSTF recommended screening all older people for colorectal cancer. In a 2008 update, the USPSTF continues to recommend screening, using fecal occult blood tests (FOBTs), sigmoidoscopy, or colonoscopy, beginning at age 50 and continuing through age 75. Recommendation: A (high certainty that the net benefit is substantial). The task force recommends against routine screening for people who are 76 to 85 years old. Recommendation: C (screening might be beneficial in an individual patient, but moderate certainty exists that the net benefit is small). It also recommends against screening people who are older than 85. Recommendation: D (moderate certainty that benefits of screening do not outweigh harms). Finally, the USPSTF concluded that insufficient evidence exists to recommend fecal DNA testing or computed tomographic (CT) colonography for colorectal cancer screening. Recommendation: I (insufficient evidence exists about benefits and harms). The task force rationalizes the upper age limits for screening by noting that mortality benefits of such screening are realized only after about 5 years.
A systematic review showed that newer FOBTs are more sensitive, but less specific, than older versions and that immunochemical FOBTs are more sensitive than, and can be as specific as, standard FOBTs. Stool DNA testing is not superior to FOBTs. CT colonography is more sensitive than FOBTs but, in addition to involving radiation exposure, requires subsequent colonoscopy for confirmatory biopsy and detects extracolonic lesions that might require follow-up. Colonoscopy is not 100% sensitive and is more harmful (because of perforation risk) than other tests.
A simulation model showed these strategies to be similarly effective and preferred:
Colonoscopy every 10 years
Annual high-sensitivity FOBT (e.g., Hemoccult SENSA, fecal immunochemical testing)
Flexible sigmoidoscopy every 5 years, with interim high-sensitivity FOBT at 2 to 3 years
Comment: This updated recommendation reflects a state-of-the-art approach (involving both systematic review and decision analysis) to determining preventive care guidelines. Earlier this year, guidelines from a Multi-Society Task Force (JW Mar 27 2008), based in part on expert opinion, included controversial recommendations for using CT colonography and stool DNA testing. That the USPSTF, which relies more exclusively on published evidence, did not recommend these tests is not surprising. The most notable change for clinical practice is the upper age limit for screening.
— Richard Saitz, MD, MPH, FACP, FASAM
Published in Journal Watch General Medicine October 28, 2008
Citation(s):
Zauber AG et al. Evaluating test strategies for colorectal cancer screening: A decision analysis for the U.S. Preventive Services Task Force. Ann Intern Med 2008 Oct 6