Prognostic Significance of Pre-treatment Systemic Immune Inflammation Index (SIII) in Patients with Advanced Epithelial Ovarian Cancer Treated with Neoadjuvant Chemotherapy

Abstract

Introduction: The Systemic Immune-Inflammation Index (SIII), derived from peripheral blood parameters, reflects the balance between host inflammation and immune response. Although its prognostic value has been demonstrated in several malignancies, its role in epithelial ovarian cancer treated with neoadjuvant chemotherapy (NACT) remains unclear. The primary objective of this study was to evaluate the prognostic significance of pre-treatment SIII in patients with advanced epithelial ovarian cancer undergoing NACT.

Materials and Methods: We retrospectively analysed patients with FIGO stage II-IV epithelial ovarian cancer treated with NACT followed by interval debulking surgery (IDS) or completion surgery at Dr. B. Borooah Cancer Institute, Guwahati, India, between 1 January 2019 and 30 June 2023. Pre-treatment SIII was calculated as (platelet count × neutrophil count)/lymphocyte count. Patients were stratified into high- and low-SIII groups based on a receiver operating characteristic (ROC)-derived cut-off determined using the Youden Index for overall survival (OS). Progression-free survival (PFS) and OS were evaluated using Kaplan-Meier analysis and Cox proportional hazards regression. A two-sided p-value <0.05 was considered statistically significant.

Results: Among 284 patients, the median age was 52 years, and high-grade serous carcinoma was present in 76%. With a median follow-up of 41 months, median PFS was 19.7 months versus 10.5 months (p<0.001), and median OS was 37.8 months versus 21.4 months (p<0.001), in the low- and high-SIII groups, respectively. On multivariable analysis, after adjusting for age, FIGO stage, and residual disease following IDS, high SIII remained an independent predictor of poor PFS (HR 2.03; 95% CI 1.36-3.04; p<0.001). High SIII also independently predicted worse OS (HR 2.42; 95% CI 1.52-3.85; p<0.001). Patients with high SIII more frequently experienced progression at multiple sites (27.8% vs. 16.7%) and had higher rates of progression involving ascites (10.3% vs. 4.6%), pleural/lung metastases (7.1% vs. 2.8%), and brain metastases (3.2% vs. 0.9%). Conversely, patients with low SIII had higher rates of isolated vault/pelvic recurrence (23.1% vs. 14.3%) and nodal recurrence (16.7% vs. 7.9%).

Conclusion: Pre-treatment SIII is a simple, cost-effective, and independent prognostic biomarker for survival in advanced epithelial ovarian cancer treated with NACT. It may aid in individual risk stratification and treatment tailoring.