A Novel Non-Invasive Biomarker for Gastric Cancer: Monocyte-to-HDL Ratio and Clinicopathological Parameters in Predicting Survival Outcomes

<b>Objective</b>: This study aimed to investigate the prognostic value of the preoperative monocyte-to-high-density lipoprotein cholesterol ratio (MHR) and clinicopathological parameters for predicting survival outcomes in patients undergoing curative-intent gastrectomy for gastric adenocarcinoma. <b>Methods</b>: This retrospective cohort study analyzed data from 304 patients with histopathologically confirmed gastric adenocarcinoma who underwent curative-intent gastrectomy with standardized D1+ or D2 lymphadenectomy. The MHR was calculated using preoperative monocyte counts and HDL cholesterol levels. Patients were dichotomized based on the optimal MHR cutoff determined via receiver operating characteristic curve analysis with the Youden index. Survival outcomes, including overall survival (OS) and progression-free survival (PFS), were assessed using Kaplan-Meier analysis and compared with log-rank tests. <b>Results</b>: ROC analysis determined an optimal MHR cutoff of ≥11.02 (AUC: 0.654; 95% CI: 0.59-0.718), yielding sensitivities and specificities of 62.6% and 62.4%, respectively. Patients with an elevated MHR (≥11.02) had worse 5-year OS (51.4 vs. 72.2%; <i>p</i> < 0.001) and PFS (65.2 vs. 80.5%; <i>p</i> = 0.003). In the multivariate Cox regression model, elevated MHR emerged as an independent predictor of disease progression (HR: 1.93; 95% CI: 1.17-3.18; <i>p</i> = 0.010), while parameters such as signet ring cell histology, lymphovascular invasion, and perineural invasion were significant in univariate analyses but not in the adjusted multivariate model. <b>Conclusions</b>: MHR should not be regarded as a definitive predictor in isolation but rather as a cost-effective, readily obtainable adjunct within a broader preoperative risk assessment framework. Integration with other inflammation-based and clinicopathological factors may enhance predictive performance and clinical applicability.