Optimizing colorectal cancer screening by race and sex: Microsimulation analysis II to inform the American Cancer Society colorectal cancer screening guideline

Abstract

Background: Colorectal cancer (CRC) risk varies by race and sex. This study, 1 of 2 microsimulation analyses to inform the 2018 American Cancer Society CRC screening guideline, explored the influence of race and sex on optimal CRC screening strategies.

Methods: Two Cancer Intervention and Surveillance Modeling Network microsimulation models, informed by US incidence data, were used to evaluate a variety of screening methods, ages to start and stop, and intervals for 4 demographic subgroups (black and white males and females) under 2 scenarios for the projected lifetime CRC risk for 40-year-olds: 1) assuming that risk had remained stable since the early screening era and 2) assuming that risk had increased proportionally to observed incidence trends under the age of 40 years. Model-based screening recommendations were based on the predicted level of benefit (life-years gained) and burden (required number of colonoscopies), the incremental burden-to-benefit ratio, and the relative efficiency in comparison with strategies with similar burdens.

Results: When lifetime CRC risk was assumed to be stable over time, the models differed in the recommended age to start screening for whites (45 vs 50 years) but consistently recommended screening from the age of 45 years for blacks. When CRC risk was assumed to be increased, the models recommended starting at the age of 45 years, regardless of race and sex. Strategies recommended under both scenarios included colonoscopy every 10 or 15 years, annual fecal immunochemical testing, and computed tomographic colonography every 5 years through the age of 75 years.

Conclusions: Microsimulation modeling suggests that CRC screening should be considered from the age of 45 years for blacks and for whites if the lifetime risk has increased proportionally to the incidence for younger adults. Cancer 2018;124:2974-85. © 2018 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society.

Keywords: colorectal neoplasms; decision modeling; early detection of cancer; guidelines; personalized medicine.

Figure 1

Illustration of the selection algorithm for model‐recommendable strategies. Each dot represents the hypothetical outcome for a single screening strategy. The bold line is the efficient frontier connecting efficient strategies (not plotted as separate dots). Dashed lines represent thresholds imposed by the decision algorithm: the efficiency criterion ensures that recommended strategies are efficient in terms of the yield in LYG for any level of COL requirement, the benefit criterion ensures that LYG do not lag far behind a selected reference strategy, and the burden‐to‐benefit criterion ensures that the incremental number of required COLs per LYG does not exceed a predefined number. The shaded area encompasses strategies fulfilling all 3 decision criteria. The model‐recommended strategy is the strategy within this area with the highest predicted number of LYG. COL indicates colonoscopy; LYG, life‐years gained.

Figure 2

Lifetime number of colonoscopies and LYG for colonoscopy screening strategies under 2 scenarios for CRC risk by model and demographic subgroup. Colors reflect the screening interval (blue, 15 years; pink, 10 years; green, 5 years), symbols reflect the starting age (diamonds, 55 years; circles, 50 years; squares, 45 years), and the filling of the symbols reflects the end age (empty, 75 years; crossed, 80 years; and full, 85 years). Efficient and near‐efficient strategies are labeled, with efficiency assessed among all evaluated colonoscopy‐based screening strategies. In the stable‐risk scenario, the risk within each age‐, race‐, and sex‐specific demographic subgroup was assumed to have remained stable over time since the early screening phase in the United States (1975‐1979 for SimCRC and 1990‐1994 for MISCAN). In the increased‐risk scenario, the CRC risk was increased proportionally to observed trends in CRC incidence among adults younger than 40 years. Estimated incidence rate ratios were 1.80 to 1.90 for white females (range across models), 1.24 to 1.27 for black females, 2.07 to 2.13 for white males, and 1.41 to 1.56 for black males. CRC indicates colorectal cancer; LYG, life‐years gained; MISCAN, Microsimulation Screening Analysis; SimCRC, Simulation Model of Colorectal Cancer.