Dr. David Lieberman
Other CRC screening programs begin with a risk-stratification test, which, if positive, would identify high-risk individuals who should have colonoscopy. The fecal immunochemical test (FIT) is now widely accepted in the United States and other countries. One-time sensitivity for CRC is 60%-85%, but the detection rate for advanced adenomas is less than 50%. Therefore, a FIT program depends on repeat testing at 1- to 2-year intervals to detect high-risk individuals who were missed on earlier rounds of screening. Adherence to repeat testing in clinical practice may be poor, which could negatively impact the overall effectiveness of the screening program.
There are several other screening options that are not "preferred" at this time. Flexible sigmoidoscopy is effective in RCTs but not well accepted in the United States or elsewhere. Stool DNA studies are promising, but the most recent large study has not yet been published. Imaging with CT or MR is costly, can lead to evaluations of extraintestinal findings, and may miss important flat lesions.
In 2013, the two primary CRC screening choices in the United States are FIT and colonoscopy. There is currently no evidence that either program produces a greater reduction in CRC incidence and mortality. There are several studies (from Spain, Nordic countries, and U.S. VA hospitals) that directly compare these programs in randomized trials. At this point, there is not a clear preferred screening program. Ultimately, programmatic adherence and quality will be critical variables that will determine the relative effectiveness of each program.
David Lieberman, M.D., is professor of medicine and chief of the division of gastroenterology and hepatology, Oregon Health and Science University, Portland.
