Development and pilot validation of the MIS gastric score for risk stratification in minimally invasive gastric cancer surgery: a single-center proof-of-concept for a future multicenter network

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Postoperative survival in gastric cancer (GC) surgery is increasingly measured by 90-day benchmarks, which reflect the complex perioperative cascade better than traditional 30-day metrics. Our primary objectives were to evaluate our institutional outcomes against international standards and to develop a preoperative risk-stratification tool (the MIS Gastric Score) capable of identifying patients at a high risk of developing major postoperative morbidity. We conducted an institutional cohort study involving 39 consecutive patients who underwent elective minimally invasive gastrectomy for GC between January 2022 and December 2025. This specialized series was analyzed as a foundational pilot dataset to establish the mathematical proof-of-concept and clinical feasibility of a novel preoperative risk-stratification tool before scaling up to a broad multicenter network. The primary endpoint was 90-day major morbidity, defined as a Clavien-Dindo score ≥ III. Independent risk factors were isolated using multivariate logistic regression analysis. The MIS Gastric Score was constructed by assigning weighted integers based on regression coefficients, and its performance was validated using Receiver Operating Characteristic (ROC) analysis and the Youden Index (J). Major postoperative morbidity occurred in 33.3% of the cohort, while the 90-day mortality rate reached 12.8%. When benchmarked against the international HOLD Study dataset, our major complication rate was statistically equivalent, but our mortality rate was significantly higher, reflecting a highly complex and frail regional demographic cluster. The composite MIS Gastric Score—incorporating hypoalbuminemia (< 3.5 g/dL), ASA Score ≥ III, and Poorly Cohesive Carcinoma (PCC) histopathological phenotype—demonstrated high discriminative accuracy (AUROC: 0.78; 95% CI: 0.61–0.94) and achieved an excellent Negative Predictive Value (85.2%) at its optimal clinical threshold. The MIS Gastric Score provides a robust, clinically intuitive, and biological-physiological “rule-out” framework for major complications following minimally invasive gastrectomy. Despite the inherent limitations of the pilot cohort size, this preliminary study establishes a validated methodological baseline and confirms the clinical feasibility of a score-guided perioperative algorithm, serving as an ideal structural blueprint for an upcoming multi-institutional prospective trial.