Predictive potential of pretreatment pepsinogen and platelet-to-lymphocyte ratios for postoperatively confirmed perineural invasion in gastric cancer patients receiving paclitaxel-based chemotherapy followed by radical surgery

Background: Perineural invasion (PNI) predicts poor prognosis in gastric cancer (GC) but lacks convenient preoperative biomarkers. Objectives: To investigate the predictive value of pretreatment platelet-to-lymphocyte ratio (PLR) and pepsinogen ratio (PGR) for postoperatively confirmed PNI in GC patients receiving paclitaxel-based chemotherapy followed by radical surgery. Methods: We retrospectively analyzed the medical records and clinical data of 110 patients with gastric cancer who underwent radical resection after paclitaxel-based neoadjuvant chemotherapy (from June 2023 to June 2025). Patients were divided into PNI-positive (n=45) and PNI-negative (n=65) groups. LASSO and logistic regression identified independent predictors. ROC curves, calibration, DCA and Spearman correlation were performed. Results: Of the 110 patients, 45 were PNI-positive and 65 were PNI-negative. Compared with the PNI-negative group, the PNI-positive group had significantly higher proportions of elevated CA19-9, increased tumor thickness, elevated PLR, diffuse/mixed Lauren type, Borrmann type III, T3-4 invasion, lymph node metastasis, TNM stage II/III and tumor diameter ≥5 cm, but significantly lower PGR (all P<0.05). LASSO identified nine non-zero coefficient indicators: CA19-9, tumor thickness, PLR, PGR, Lauren classification, Borrmann type III, tumor invasion, lymph node metastasis and TNM stage. Elevated PLR and advanced TNM stage were risk factors, while elevated PGR was a protective factor. ROC analysis showed apparent AUCs for PLR, TNM stage, PGR and the combined model of 0.786, 0.834, 0.807 and 0.851, respectively. PGR was negatively correlated with PNI (r = -0.749), whereas PLR (r = 0.698) and TNM stage (r = 0.751) were positively correlated. Conclusion: Pretreatment PLR and PGR show moderate predictive value for PNI in GC patients after paclitaxel chemotherapy, with slightly improved combined performance when TNM stage is added. External validation is required before clinical application.