Prognostic nutritional index in evaluating the prognosis of ICIs in patients with advanced esophageal squamous carcinoma.

OBJECTIVE: This study aimed to investigate the association between the Prognostic Nutritional Index (PNI) and the prognosis of advanced esophageal squamous cell carcinoma (ESCC) patients treated with immune checkpoint inhibitors (ICIs). METHODS: We retrospectively analyzed the clinical data of 157 advanced ESCC patients who received ICIs therapy at Hengshui People's Hospital. The PNI was calculated based on serum albumin levels and lymphocyte counts. The predictive value of PNI for disease progression in advanced ESCC patients was evaluated using receiver operating characteristic (ROC) curve analysis. RESULTS: Among 157 patients with advanced ESCC, the complete response (CR) rate was 0.64% (1/157), partial response (PR) rate was 47.13% (74/157), stable disease (SD) rate was 38.22% (60/157), and progressive disease (PD) rate was 14.01% (22/157). The median progression-free survival (PFS) was 14.2 months. During the follow-up period, 80 patients died, leading to a mortality rate of 50.96%. The CR+PR group showed significantly higher albumin levels, lymphocyte counts, and PNI compared to the PD group (p< 0.05). The area under the curve (AUC) of PNI for predicting disease progression was 0.770 (95% CI: 0.696-0.833), with a sensitivity of 86.36% and specificity of 58.52%. Based on the cutoff value, patients were stratified into high-PNI (>44.4, n=82) and low-PNI (ow-PNI n=75) groups. The high-PNI group demonstrated significantly lower disease progression rates compared to the low-PNI group (p< 0.05). Kaplan-Meier analysis revealed that advanced ESCC patients in the high-PNI group had significantly longer PFS and overall survival (OS) than those in the low-PNI group (p< 0.05). The disease-free survival rate after ICIs therapy was 96.34% in the high-PNI group compared to 74.67% in the low-PNI group (Log-rank χ²=18.332, p< 0.05). The 3-year survival rate post-ICIs was 64.93% in the high-PNI group compared to 33.75% in the low-PNI group (Log-rank χ²=12.378, p< 0.05). Lymphocyte count and PNI as independent prognostic factors for PFS in advanced ESCC patients (p< 0.05), while poor differentiation, smoking history, and PNI were independent predictors for OS (p< 0.05). CONCLUSION: PNI is associated with the efficacy of ICI therapy and prognosis in patients with advanced ESCC, suggesting its potential as a promising prognostic stratification marker. However, the clinical utility of PNI as an independent biomarker requires further validation through prospective, multicenter studies with larger sample sizes.