Strategies for screening for colorectal carcinoma.

Four tests commonly used in screening strategies to detect colorectal cancer were examined from a cost-effectiveness perspective. Thirteen combinations of the tests were evaluated. Evaluating a positive fecal occult blood test with a double-contrast barium enema study, followed, if necessary, by colonoscopy, is the most cost-effective strategy for individuals at average risk. An alternative screening strategy for higher-risk individuals or for populations in which the frequency of adenomatous polyps is higher is to follow a positive fecal occult blood test directly with colonoscopy. Sensitivity analysis demonstrated that the superior cost-effectiveness of these two strategies compared with the other 11 modeled strategies is almost independent for reasonable alterations in test cost and for the sensitivities and specificities of the procedures. The major contributing factor to the diagnostic cost is the frequency of adenomatous polyps. The major contributing factor to the marginal cost per year of extended life is the frequency of cancer.