Estimation of Benefits, Burden, and Harms of Colorectal Cancer Screening Strategies

Modeling Study for the US Preventive Services Task Force

Published in: JAMA, 2016

Posted on RAND.org on June 21, 2016

by Amy B. Knudsen, Ann G. Zauber, Carolyn M. Rutter, Steffie K. Naber, V. Paul Doria-Rose, Chester Pabiniak, Colden Johanson, Sara E. Fischer, Iris Lansdorp-Vogelaar, Karen M Kuntz

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Research Question

  1. What are the most effective strategies for colorectal cancer screening?

IMPORTANCE: The US Preventive Services Task Force (USPSTF) is updating its 2008 colorectal cancer (CRC) screening recommendations. OBJECTIVE: To inform the USPSTF by modeling the benefits, burden, and harms of CRC screening strategies; estimating the optimal ages to begin and end screening; and identifying a set of model-recommendable strategies that provide similar life-years gained (LYG) and a comparable balance between LYG and screening burden. DESIGN, SETTING, AND PARTICIPANTS: Comparative modeling with 3 microsimulation models of a hypothetical cohort of previously unscreened US 40-year-olds with no prior CRC diagnosis. EXPOSURES: Screening with sensitive guaiac-based fecal occult blood testing, fecal immunochemical testing (FIT), multitarget stool DNA testing, flexible sigmoidoscopy with or without stool testing, computed tomographic colonography (CTC), or colonoscopy starting at age 45, 50, or 55 years and ending at age 75, 80, or 85 years. Screening intervals varied by modality. Full adherence for all strategies was assumed. MAIN OUTCOMES AND MEASURES: Life-years gained compared with no screening (benefit), lifetime number of colonoscopies required (burden), lifetime number of colonoscopy complications (harms), and ratios of incremental burden and benefit (efficiency ratios) per 1000 40-year-olds. RESULTS: The screening strategies provided LYG in the range of 152 to 313 per 1000 40-year-olds. Lifetime colonoscopy burden per 1000 persons ranged from fewer than 900 (FIT every 3 years from ages 55-75 years) to more than 7500 (colonoscopy screening every 5 years from ages 45-85 years). Harm from screening was at most 23 complications per 1000 persons screened. Strategies with screening beginning at age 50 years generally provided more LYG as well as more additional LYG per additional colonoscopy than strategies with screening beginning at age 55 years. There were limited empirical data to support a start age of 45 years. For persons adequately screened up to age 75 years, additional screening yielded small increases in LYG relative to the increase in colonoscopy burden. With screening from ages 50 to 75 years, 4 strategies yielded a comparable balance of screening burden and similar LYG (median LYG per 1000 across the models): colonoscopy every 10 years (270 LYG); sigmoidoscopy every 10 years with annual FIT (256 LYG); CTC every 5 years (248 LYG); and annual FIT (244 LYG). CONCLUSIONS AND RELEVANCE: In this microsimulation modeling study of a previously unscreened population undergoing CRC screening that assumed 100% adherence, the strategies of colonoscopy every 10 years, annual FIT, sigmoidoscopy every 10 years with annual FIT, and CTC every 5 years performed from ages 50 through 75 years provided similar LYG and a comparable balance of benefit and screening burden.

Key Findings

  • Four screening strategies were recommendable, providing similar screening benefit relative to burden: colonoscopy every 10 years, sigmoidoscopy every 10 years with annual fecal immunochemical (FIT) testing, CT colonography every five years, and annual FIT.
  • Among individuals screened from the age of 50 to 75, there was little benefit to continuing screening after age 75 relative to the increase in colonoscopies that would be needed.
  • Model results suggest that starting screening at 45 years of age may provide a better balance between life years gained and screening burden than starting at age 50, but current empirical evidence does not support changing the recommendation to start at age 50.
  • Three independently developed microsimulation models with differing assumptions produced similar results, including consistent predictions of the relative utility of screening modalities, and rankings within classes of modalities.

Recommendation

These analyses were carried out to inform recommendations by the U.S. Preventive Services Task Force's recommendations. New screening guidelines modify 2008 guidelines by adding computed tomography (CT) colonography and the multitargeted stool DNA test as recommendable tests, and by noting that some individuals may benefit from screening after age 75.

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