OBJECTIVES

Colorectal cancer (CRC) screening models are valuable tools for projecting long-term effects and resource use for policy decision-making. A new Discrete Event simulation model for the natural history of Colorectal cancer from the Adenoma and Serrated neoplasia pathways (DECAS) was recently developed and calibrated using the German screening colonoscopy registry data, which consist of 5.2 million screening participants between 2003-2014. It was validated against the German national cancer registry data. We aimed to use DECAS to estimate the length of protective effects of colonoscopy screening and the amount of colonoscopy needed in the German context.

METHODS

We used DECAS to simulate a cohort of averaged-risk individuals from age of 20 to 90 for three scenarios: (1) no screening; (2) one colonoscopy at age of 55; (3) two colonoscopies at age of 55 and 65. In the base-case analysis, we assumed the adenoma pathway accounting for 85% of the CRC development and the serrated pathway for the other 15%, as well as a 100% uptake of screening and surveillance colonoscopies. Outcomes of interest were hazard ratios (HR) of CRC-specific mortality under each screening scenario comparing to no screening, and the number of colonoscopies required.

RESULTS

DECAS predicted HRs of CRC-specific mortality at approximately 0.2 for both screening scenarios after 25 years of follow up, and the trend of both mortality HRs was still decreasing. The average numbers of colonoscopies required were 1,300 and 2,174 per 1,000 for once and twice colonoscopy screening, respectively. We also varied alternative screening and surveillance participation rates for sensitivity analyses.

CONCLUSIONS

The modeling results from DECAS confirmed the long-term protective effects of colonoscopy screening and provided an estimation of the number of colonoscopies required in the German context. We will further apply DECAS to perform economic evaluations on various CRC screening strategies and policies.