The long-term population impact of endoscopic screening programmes on disease burdens of gastric cancer in China: A mathematical modelling study

Abstract

Background: Gastric cancer (GC) incidence and mortality in China remained high due to delayed diagnosis and accounted for about half of the world's GC cases and deaths. Early detection with endoscopic screening and consequent timely treatment can significantly improve survival. This study aimed to explore the long-term population impact of endoscopic screening on national GC disease burdens in China.

Methods: Most of previous studies investigated the disease burdens of cancer using Markov model or age-period-cohort (APC) model, which are difficult to estimate the population size of undiagnosed cases. In this paper, we proposed a new dynamic compartmental model based on GC natural history and calibrated model outputs to diagnosed GC cases and GC-related death counts using Markov Chain Monte Carlo methods. We investigated the impact of screening strategies with various coverage (10%, 40%, 70%) and frequency (every 1, 3, 5 years) on disease burdens.

Results: We estimated that 2.22 (95%CI: 1.97-2.47) million Chinese are living with GC in 2019, among which, 42.7% (40.3-45.0%) remained undiagnosed. Without systematic screening, we projected 10.46 (9.07-11.86) million incident cases and 7.35 (6.59-8.11) million GC-related deaths over the next 30 years (2019-2049). Screening with coverage rate at 10%, 40%, 70% every 3 years could prevent 0.85 (0.63-1.06), 2.32 (1.79-2.86), and 3.04 (2.38-3.70) million incident cases, and prevent 1.17 (1.01-1.32), 3.08 (2.70-3.46), and 3.93 (3.46-4.40) million deaths respectively, compared with 'no screening' scenario. Screening would substantially increase the number of diagnosed GC cases within the first three years of program initiation, but this number would quickly reduce below 'no screening' scenario. Three-yearly screening at the above coverage rates would reduce the proportion of undiagnosed GC cases to 38.8% (36.9-40.7%), 25.5% (23.4-27.6%), and 17.8% (16.0-19.6%) by 2049, respectively. Delaying implementation of the screening program would substantially reduce its effectiveness.

Conclusions: Initiating national endoscopic screening programmes would likely have a major effect on reducing GC incidence and mortality in China. Health resources should be substantially increased and directed to treatment of GC to cope with the initial rise in diagnosed GC cases.

Keywords: Deaths; Dynamic compartmental model; Endoscopic screening; Gastric cancer; Incident cases; Prevalent cases.