Abstract

Background: Predicting therapeutic durability remains a clinical challenge in patients with EGFR-mutant advanced non-small cell lung cancer (NSCLC). The Systemic Inflammation Response Index (SIRI), a multi- 300 TẠP CHÍ Y DƯỢC HUẾ - HUE JOURNAL OF MEDICINE AND PHARMACY ISSN 3030-4318; eISSN: 3030-4326 parameter biomarker based on neutrophil, monocyte, and lymphocyte counts, reflects the complex interplay between host immunity and systemic inflammation. Objective: To investigate the prognostic significance of baseline SIRI for progression-free survival (PFS) in patients receiving first-generation tyrosine kinase inhibitors (TKIs). Materials and Methods: A retrospective–prospective (ambispective) cohort study with longitudinal follow-up was conducted on 94 patients with advanced EGFR-mutant NSCLC treated with first-generation TKIs (Gefitinib or Erlotinib) at Hue Central Hospital, Da Nang Oncology Hospital, and Hue University of Medicine and Pharmacy Hospital. Pretreatment SIRI was calculated from absolute peripheral blood counts. The optimal SIRI cut-off for predicting disease progression was determined using ROC curve analysis. PFS distributions were assessed via Kaplan-Meier estimates and Log-rank tests. A multivariate Cox proportional hazards model was employed to identify independent prognostic factors. Results: The mean age of the cohort was 65.83 ± 10.60 years. The optimal baseline SIRI cut-off for predicting disease progression was 2.65 (AUC = 0.721; p = 0.001). The overall median PFS was 9.0 months. Patients in the low-SIRI group (≤ 2.65) achieved a significantly superior median PFS compared to those in the high-SIRI group (11.0 vs. 7.0 months; Log-rank p < 0.001). Multivariate Cox analysis confirmed that an elevated pretreatment SIRI was an independent predictor of shorter PFS (Hazard Ratio [HR] = 2.39; 95% CI: 1.44 - 3.94; p = 0.001). Other clinicopathological parameters, including age, BMI, ECOG performance status, and smoking history, did not retain independent prognostic weight in this model (p > 0.05). Conclusion: Pretreatment Systemic Inflammation Response Index (SIRI) is an independent, non-invasive, and cost-effective biomarker that independently predicts PFS in NSCLC patients on first-generation EGFR- TKIs. Incorporating SIRI into routine clinical evaluation facilitates improved risk stratification and supports more personalized management strategies in the targeted therapy era.