An Opportunistic Screening Strategy for Gastric Cancer Based on Questionnaire and Sequential Serology: A Hospital-Based Cross-Sectional Study (SIGES)

<b>Objectives:</b> In the absence of massive screening programs, it is imperative to develop and validate a candidate selection strategy for opportunistic endoscopic screening (OES) targeting the early detection of gastric cancer. <b>Methods:</b> A hospital-based cross-sectional study was conducted, enrolling both health check-up controls and gastric cancer patients. Data collection included two components: (1) a questionnaire including demography, self-reported comorbidities, and family history of cancers; (2) serology including hemoglobin, carcinoembryonic antigen (CEA), and carbohydrate antigen 19-9 (CA19-9). Associations between potential variables and gastric cancer risk were assessed and the predictive efficacy of these risk factors was quantified. Sequentially, risk stratification scoring systems were constructed and their cost-effectiveness profiles were evaluated. <b>Results:</b> A total of 58,218 participants were included in the analysis, among whom 619 (1.1%) were gastric cancer patients. Multivariate analyses identified male, age >40 years, family history of gastric cancer, comorbidities of upper digestive tract benign diseases (UDTBDs), anemia, and elevated serum CEA and/or CA19-9 as independent risk factors of increasing gastric cancer risk. Cost-effectiveness analysis demonstrated that individuals, especially those symptomatic, presenting any of following conditions should be recommended for OES: (1) age ≥50 years, (2) family history of gastric cancer, and/or (3) comorbid UDTBDs. Elsewise, unclear anemia and/or elevated serum CEA and/or CA19-9 presenting among males and/or persons 41-50 years of age should be considered for OES. Notably, this selection strategy achieved a detection rate comparable to that of alternative protocols while yielding superior cost-effectiveness outcomes. <b>Conclusions:</b> The integrated strategy combining questionnaire and sequential serology represents an effective and cost-effective approach to identifying high-risk candidates for gastric cancer OES. Further investigations are warranted to develop more precise and tailored screening and surveillance protocols, with the aim of optimizing both detection rates and cost-effectiveness in clinical practice.