On Nov. 4, the Clinical Guidelines Committee of the American College of Physicians (ACP) issued a guidance statement for physicians on colorectal cancer (CRC) screening for adults with average risk. The main recommendations, published in the Annals of Internal Medicine, were the following:
- All adults ages 50 to 75 of average risk should be screened
- Suggested tests and intervals include: fecal immunochemical testing (FIT) or high-sensitivity guaiac-based fecal occult blood testing (gFOBT) every 2 years, colonoscopy every 10 years, or flexible sigmoidoscopy every 10 years plus FIT every 2 years
- Screening should not be done in average-risk adults older than age 75 or in adults with a life expectancy of less than 10 years
The authors said the aim was to reconcile the differing recommendations from various organizations.
Below is a response from Rich Wender, MD, our chief cancer control officer:
"The ACP guidance statement for CRC screening confirms the high value of screening adults for colorectal cancer. The statement also confirms the value of a variety of screening strategies, and providing patients with a choice of options. Validating the importance of screening for the second leading cause of cancer related death in the United States when men and women are combined, once again affirms what has been an accepted and highly valued preventive practice for years. And additional guidance might encourage some clinicians to make this a higher priority.
Because of the methods used by the ACP, this new statement may be a source of confusion for some clinicians and the general public. Because of their heavy reliance on clinical trials, particularly randomized clinical trials, and the decision not to rely on modeling data, the potential recommendations are inevitably confined to those approaches to screening that were actually tested in these trials. No trials evaluated beginning screening prior to age 50. In addition, these trials are all somewhat older and some should be judged as being out of date in that they were conducted before the changing epidemiology of CRC and the shift to earlier onset disease was known. It is highly unlikely that another large randomized trial of CRC screening will occur in the U.S., and even if one were to be designed comparing starting ages, the results would not be known for many years. Thus, the ACP methods permit no clear pathway to ever recommend a change in starting age, as the ACS did last year.
Research conducted by the ACS conclusively demonstrates that the risk for CRC in individuals under age 50 has increased dramatically, particularly for rectal cancer. Modeling based on these new trends provides consistent and compelling evidence that starting screening at age 45 is more efficient than starting at age 50.
One way to look at this: The risk of colorectal cancer in people age 45 is now virtually the same as the risk at age 50 when some of the clinical trials were first conducted. And the trend of rising risk in young adults is going to continue, and is occurring in many countries around the world.
While relying on trials is an important and conservative approach to determine the efficacy of screening, once that efficacy is established, we need to move beyond the trials when we need to update a screening guideline based on new data, such as evidence of changing risk of disease. Using other approaches, like modeling, adds to the precision of guidelines."