Predictive value of peripheral blood inflammatory biomarkers in immunotherapy for extensive-stage small-cell lung cancer

Background The clinical management of extensive-stage small-cell lung cancer (ES-SCLC) is challenged by the lack of reliable biomarkers to identify patients resistant to first-line immunotherapy. Peripheral blood inflammatory biomarkers are emerging as promising prognostic tools in oncology, but their predictive role in ES-SCLC remains unclear. Methods We conducted a multicenter retrospective study of patients with ES-SCLC treated between January 2020 and January 2024 in two hospitals. Baseline clinical data and peripheral blood inflammatory indices—including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), mean platelet volume (MPV), modified Glasgow Prognostic Score (mGPS), and Lung Immune Prognostic Index (LIPI)—were collected before treatment and after four cycles of immunochemotherapy. Optimal cut-off values were determined using X-tile software, and dynamic changes (Δ) were calculated. Survival analyses were performed with Kaplan–Meier and Cox proportional hazards models. Prognostic nomograms were developed and validated with calibration curves and receiver operating characteristic (ROC) analysis. Results A total of 212 patients were included, with a median follow-up of 16.2 months. The objective response rate (ORR) and disease control rate (DCR) were 46.7% and 72.2%, respectively. The median progression-free survival (PFS) and overall survival (OS) were 8.4 and 15.3 months. High pre-treatment NLR, high pre-treatment MPV, increased ΔNLR, pre-mGPS score of 2, and elevated ΔmGPS or ΔLIPI were independent predictors of shorter PFS. For OS, high pre-treatment NLR, pre-mGPS score of 2, pre-LIPI score of 2, and increased ΔNLR, ΔmGPS, or ΔLIPI were independent risk factors. The nomograms demonstrated good predictive accuracy for both PFS and OS, with area under the curve (AUC) values ranging from 0.728 to 0.946. Conclusion Peripheral blood inflammatory biomarkers, particularly pre-NLR, ΔNLR, pre-mGPS, and ΔLIPI, are independent predictors of outcomes in ES-SCLC patients receiving first-line immunotherapy. The proposed nomograms provide effective tools for individualized risk stratification and treatment optimization.