The predictive value of prognostic immune and nutritional index in esophageal squamous cell carcinoma receiving neoadjuvant immunochemotherapy: a retrospective propensity score matching study

Background/aim The prognostic immune and nutritional index (PINI) has been increasingly recognized as a significant parameter associated with clinical outcomes in multiple cancers. Nevertheless, its prognostic role in esophageal squamous cell carcinoma (ESCC) undergoing neoadjuvant immunochemotherapy (NICT) remains unexplored. Methods This retrospective research enrolled 193 ESCC treated with NICT. The threshold for PINI was determined using the restricted cubic spline (RCS) model. To control for potential confounders, propensity score matching (PSM) was applied. We subsequently assessed the correlations between PINI and both disease-free survival (DFS) and overall survival (OS). Cox proportional hazards regression models were employed to quantify these associations, with results expressed as hazard ratios (HRs) and corresponding 95% confidence intervals (CIs). Results The RCS model established an optimal PINI cutoff at 3.320, stratifying all patients into low (n=97) and high (n=96) cohorts. To address potential confounding, PSM generated 64 balanced pairs. Patients in the low cohort demonstrated significantly worse 3-year DFS and OS compared to those with high PINI whether before (DFS: 43.3% vs. 76.0%, P<0.001; OS: 58.8% vs. 84.4%, P<0.001) or after (DFS: 48.4% vs. 68.8%, P = 0.021; OS: 64.1% vs. 81.2%, P = 0.033) PSM. Multivariate analysis confirmed PINI as an independent prognostic index for both DFS (HR = 0.423, 95% CI = 0.257-0.696, P = 0.001) and OS (HR = 0.461, 95% CI = 0.250-0.848, P = 0.013) in the pre-matched cohort. After PSM, PINI remained independently predictive of DFS (HR = 0.543, 95% CI = 0.309-0.955, P = 0.034), though not for OS. Conclusion PINI is a significant independent parameter of prognosis, especially in DFS, in patients with ESCC receiving NICT. Incorporating PINI into existing prognostic models may improve long-term risk stratification and assist in personalizing therapeutic strategies.