Evaluating Test Strategies for Colorectal Cancer Screening: A Decision Analysis for the U.S. Preventive Services Task Force

Ann G. Zauber
12 oct 2008--Background: The U.S. Preventive Services Task Force requested a decision analysis to inform their update of the recommendations for colorectal cancer screening.
Objective: To assess life-years gained and colonoscopy requirements for colorectal cancer screening strategies and identify a set of recommendable screening strategies.
Design: Decision analysis using 2 colorectal cancer microsimulation models from the Cancer Intervention and Surveillance Modeling Network.
Data Sources: Derived from the literature.
Target Population: U.S. average-risk 40-year-old population.
Perspective: Societal.
Time Horizon: Lifetime.
Interventions: Fecal occult blood tests (FOBTs), flexible sigmoidoscopy, or colonoscopy screening beginning at age 40, 50, or 60 years and stopping at age 75 or 85 years, with screening intervals of 1, 2, or 3 years for FOBT and 5, 10, or 20 years for sigmoidoscopy and colonoscopy.
Outcome Measures: Number of life-years gained compared with no screening and number of screening tests required.
Results of Base-Case Analysis: Beginning screening at age 50 years was consistently better than at age 60. Decreasing the stop age from 85 to 75 years decreased life-years gained by 1% to 4%, whereas colonoscopy use decreased by 4% to 15%. Assuming equally high adherence, 4 strategies provided similar life-years gained: colonoscopy every 10 years, annual Hemoccult SENSA (Beckman Coulter, Fullerton, California) testing or fecal immunochemical testing, and sigmoidoscopy every 5 years with midinterval Hemoccult SENSA. Hemoccult II and flexible sigmoidoscopy every 5 years alone were less effective.
Results of Sensitivity Analysis: The results were most sensitive to beginning screening at age 40 years.
Limitations: The stopping age for screening was based only on chronological age.
Conclusions: The findings support colorectal cancer screening with the following: colonoscopy every 10 years, annual screening with a sensitive FOBT, or flexible sigmoidoscopy every 5 years with a midinterval sensitive FOBT from ages 50 to 75 years.