The impact of the rising colorectal cancer incidence in young adults on the optimal age to start screening: Microsimulation analysis I to inform the American Cancer Society colorectal cancer screening guideline

Abstract

Background: In 2016, the Microsimulation Screening Analysis-Colon (MISCAN-Colon) model was used to inform the US Preventive Services Task Force colorectal cancer (CRC) screening guidelines. In this study, 1 of 2 microsimulation analyses to inform the update of the American Cancer Society CRC screening guideline, the authors re-evaluated the optimal screening strategies in light of the increase in CRC diagnosed in young adults.

Methods: The authors adjusted the MISCAN-Colon model to reflect the higher CRC incidence in young adults, who were assumed to carry forward escalated disease risk as they age. Life-years gained (LYG; benefit), the number of colonoscopies (COL; burden) and the ratios of incremental burden to benefit (efficiency ratio [ER] = ΔCOL/ΔLYG) were projected for different screening strategies. Strategies differed with respect to test modality, ages to start (40 years, 45 years, and 50 years) and ages to stop (75 years, 80 years, and 85 years) screening, and screening intervals (depending on screening modality). The authors then determined the model-recommended strategies in a similar way as was done for the US Preventive Services Task Force, using ER thresholds in accordance with the previously accepted ER of 39.

Results: Because of the higher CRC incidence, model-predicted LYG from screening increased compared with the previous analyses. Consequently, the balance of burden to benefit of screening improved and now 10-yearly colonoscopy screening starting at age 45 years resulted in an ER of 32. Other recommended strategies included fecal immunochemical testing annually, flexible sigmoidoscopy screening every 5 years, and computed tomographic colonography every 5 years.

Conclusions: This decision-analysis suggests that in light of the increase in CRC incidence among young adults, screening may be offered earlier than has previously been recommended. Cancer 2018;124:2964-73. © 2018 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society.

Keywords: advisory committees; colorectal neoplasms; early detection of cancer; incidence; models; preventive health services; theoretical.

Figure 1

Algorithm used to select model‐recommended strategies. LYG indicates life‐years gained (current recommendation is colonoscopy screening from ages 50 to 75 years every 10 years); ER, efficiency ratio. The ER is calculated as and is an incremental burden‐to‐benefits ratio. Threshold ERs of 40, 45, and 50 colonoscopies per LYG were evaluated. The stool‐based strategies (fecal immunochemical test, high‐sensitivity guaiac‐based fecal occult blood test, and multitarget stool DNA test) were combined into 1 class because they have a similar noncolonoscopy burden. CTC, computed tomographic colonography; SIG, flexible sigmoidoscopy.

Figure 2

Lifetime number of colonoscopies and life‐years gained (LYG) for colonoscopy screening strategies.