Despite much publicity and education of the public in the United States as to the efficacy of colorectal cancer screening in decreasing mortality from colorectal cancer, only 40-50 percent of eligible, average risk patients (i.e., over age 50) have been screened for colorectal cancer at the present time. The reasons for the poor compliance with recommendations are unclear, but some of the lack of screening may relate to the uncertainty as to the best and most cost-effective screening modality. The question as to which modality is most effective in detecting cancers, and the most cost effective screening strategy, has been looked at by several groups via computer-generated models. Each of these studies has indicated that colonoscopy, flexible sigmoidoscopy, and annual fecal occult blood testing are all cost-effective in terms of cost per life (years saved from death by colon cancer compared with no screening). In terms of timing, computer modeling studies have suggested that a colonoscopy every 10 years, particularly at ages 50 and 60 years, is the most cost-effective strategy for primary screening for colorectal cancer.
An editorial by David Lieberman, MD, in the December 2005 American Journal of Gastroenterology added a new dimension of complexity to the timing of screening of asymptomatic, average-risk populations by pointing out differences in race (African American populations have a higher rate of colon cancers occurring at a younger age) and gender (women may have a lower risk in their 50s compared with men; they also appear to have fewer cancers picked up on sigmoidoscopy than men). These new data may indicate that PCPs should consider starting their colon cancer screening for average-risk African American patients at age 45 instead of age 50. In addition, PCPs may wish to recognize that flexible sigmoidoscopy may not be a good choice for screening women over age 50 who appear to have more proximal rather than distal neoplasia (i.e., within the reach of the flexible sigmoidoscope) compared to men of the same age.
* Lieberman D. Race, gender, and colorectal cancer screening American Journal of Gastroenterology. 2005;100:2756–58.