Systemic Immune-Inflammatory Index Association with Survival in Patients Undergoing Trimodality Therapy for Lung Cancer

Purpose: The systemic immune-inflammation index (SII) is correlated with patient survival in various solid malignancies including non-small-cell lung cancer (NSCLC). However, limited information is available on the prognostic implication of the SII in patients undergoing trimodality therapy for stage III NSCLC. Methods: At our institution, 81 patients underwent curative intent trimodality therapy (neoadjuvant chemoradiotherapy followed by surgical resection) for stage III NSCLC from 2004 to 2019. The SII was calculated at the time of diagnosis as platelet count x neutrophil count/lymphocyte count. chi(2) analysis was used to compare categorical variables. A Kaplan-Meier analysis was performed to estimate disease-free survival (DFS), overall survival (OS), and freedom from recurrence (FFR) rates, with Cox regression used to determine absolute hazards. Results: Patients underwent neoadjuvant radiation therapy to a median dose of 4,500 cGy concurrent with a median of 3 cycles of chemotherapy (most commonly carboplatin and paclitaxel) followed by surgical resection (86.4% lobectomy and 13.6% pneumonectomy) with mediastinal lymph node dissection. At a median follow-up of 68.4 months, a low SII (<1,260) at diagnosis was independently associated with an improved OS (hazard ratio [HR]: 0.448, p = 0.004), DFS (HR: 0.366, p < 0.001), and FFR (HR: 0.325, p = 0.002). Conclusions: We identified that a low SII was associated with improved OS, DFS, and FFR in patients undergoing trimodality therapy for stage III NSCLC. The interplay of the immune system and lung cancer outcomes remains an active area of investigation for which further study is warranted.