Taishotoyama Symposium Barriers to colorectal cancer screening: economics, capacity and adherence.J Gastroenterol Hepatol 2008; 23 Suppl 2:S198-204JG
Colorectal cancer is the second leading cause of cancer death in the United States (U.S.). Fecal occult blood testing has been shown in randomized controlled trials to decrease mortality from colorectal cancer. The incidence and mortality associated with colorectal cancer has also been illustrated to be decreased with sigmoidoscopy and colonoscopy through case-control and prospective cohort studies. Current research focuses on determining which screening strategy is optimal, and how we may improve implementation. Primary screening colonoscopy may be most effective; however, this strategy would require up to 2.6 procedures per patient over their lifetime. Based on the U.S. census this equates to 7.5 million procedures annually; the current capacity in the U.S. is insufficient to provide this strategy for all eligible persons. Computed tomographic or magnetic resonance colonography (virtual colonoscopy) may be an attractive alternative, but capacity is also insufficient for implementation. Moreover, since virtual colonoscopy is a diagnostic but not therapeutic test, economic analysis has illustrated that this strategy will not be cost-effective compared to conventional colonoscopy unless it becomes much less expensive or is associated with greater adherence. Fecal DNA testing is a promising technology but current biomarkers are insufficiently sensitive to constitute a viable strategy. Newer tests such as self-propelled, self-guided endoscopes (Aer-O-Scope), 'active' endoscopes that decrease looping (Neoguide) and colon capsule endoscopy require formal evaluation through clinical trials prior to endorsement for colorectal cancer screening. Less than half of all eligible persons in the U.S. adhere to screening recommendations. Factors associated with screening adherence include the patient's level of education, income, access to health care, a family history of colon cancer, male gender and recommendation from the primary care physician. Conversely, non-adherence is associated with concern over the bowel preparation and fear of discomfort and embarrassment with the procedure. Moreover, it appears that the presence of multiple strategies may be the cause of non-adherence in many cases. Patients who are given a choice of several strategies are less likely to adhere to any strategy than patients who are recommended a single strategy. To increase adherence to colorectal cancer screening it is recommended that the patient be instructed to undergo the test to which they are most likely to adhere. Future research should focus on interventions to improve patient adherence to screening, and on developing accurate tests that will achieve high levels of adherence.