A nomogram based on systemic inflammatory markers: development and validation for predicting postoperative overall survival in gastric cancer.

Background: Gastric cancer (GC) remains a leading cause of cancer-related mortality worldwide. Emerging evidence links dysregulated lipid metabolism and chronic systemic inflammation to GC progression, and a bidirectional regulatory loop between lipid metabolism reprogramming and tumor inflammation; however, most prognostic studies have evaluated these markers in isolation. We hypothesized that integrating lipid derivatives and systemic inflammatory markers would provide complementary prognostic information. This study aimed to develop and validate a nomogram combining these markers to predict postoperative overall survival (OS) in patients with resectable GC. Methods: This retrospective study included GC patients who underwent radical gastrectomy at Affiliated Changshu Hospital of Nantong University, between January 2017 and December 2022. Inclusion criteria included radical surgery without preoperative anticancer treatment, and expected postoperative survival ≥3 months. Exclusion criteria included concurrent or prior malignancies, preoperative infection, or use of lipid-altering medications within 6 months. Fasting venous blood samples were collected preoperatively for routine blood, lipid profile, and coagulation tests using standardized automated analyzers. Fourteen composite inflammatory and lipid indices were calculated. Univariate and multivariate Cox regression analyses identified the independent predictors of overall survival (OS). A nomogram was constructed and validated using Harrell's concordance index (C-index) and calibration curves. Results: A total of 295 patients with GC were included in the study. The patients were randomized into a training group (n=197) and a validation group (n=98) (2:1 ratio). Baseline characteristics were well balanced (all P>0.05), with only alcohol consumption rate differing significantly between groups (P=0.01). Univariate and multivariate Cox regression revealed that the pathological tumor-node-metastasis (pTNM) stage [hazard ratio (HR) =2.05; 95% confidence interval (CI): 1.09-3.84; P=0.03], systemic immune-inflammation index (SII) (HR =1.99; 95% CI: 1.08-3.68; P=0.03), systemic inflammatory response index (SIRI) (HR =1.88; 95% CI: 1.02-3.45; P=0.04), and fibrinogen-to-platelet ratio (FPR) (HR =2.14; 95% CI: 1.25-3.67; P=0.006) were independent predictors of postoperative OS, positively correlating with postoperative mortality. The nomogram integrating these four variables showed satisfactory discriminative ability, with C-indices of 0.699 in the training set and 0.719 in the validation set. Calibration curves demonstrated good agreement between the predicted and observed 1-, 2-, and 3-year OS rates. Conclusions: The nomogram based on the pTNM stage, SII, SIRI, and FPR exhibits moderate prognostic performance for postoperative OS in GC patients. It provides a comprehensive tool for clinicians to assess prognosis, guiding adjuvant therapy and individualized follow-up strategies.