High Systemic Immune-Inflammation Index is an Adverse Prognostic Factor for Patients With Gastroesophageal Adenocarcinoma

OBJECTIVE: The aim of this study was to determine the clinical role of the systemic immune-inflammation index in patients with resectable adenocarcinoma of the gastroesophageal junction treated with or without neoadjuvant therapy. BACKGROUND: Adenocarcinoma of the gastroesophageal junction is an aggressive disease, with less than 20% of overall patients surviving more than 5 years after diagnosis, while currently available clinical staging for esophageal cancer is lacking necessary accuracy. The systemic immune-inflammation index (SII) based on peripheral neutrophil, lymphocyte, and platelet counts has shown a prognostic impact in various malignancies. METHODS: Data of consecutive patients undergoing esophagectomy (n = 320, 1992 to 2016) were abstracted. The cut point for high and low SII before neoadjuvant treatment and before surgery was calculated for illustration of the Kaplan-Meier curves. SII was used for the correlation with patients' clinicopathological characteristics as a continuous variable. Survival was analyzed with Cox proportional hazards models using clinical or pathological staging, adjusting for other known survival predictors. RESULTS: In both neoadjuvantly treated and primarily resected patients, high SII was significantly associated with diminished overall [hazard ratio (HR) 1.3, 95% confidence interval (95% CI) 1.2-1.4; HR 1.2, 95% CI 1.2-1.3, respectively] and disease-free survival (HR 1.3, 95% CI 1.2-1.3; HR 1.2, 95% CI 1.2-1.3, respectively). In multivariable survival analysis, SII remained an independent prognostic factor for overall survival (HR 1.3, 95% CI 1.2-1.4; HR 1.2, 95% CI 1.2-1.3, respectively) and disease-free survival (HR 1.3, 95% CI 1.2-1.3; HR 1.2, 95% CI 1.2-1.3, respectively) in primarily resected and neoadjuvantly treated patients. CONCLUSION: Elevated SII is an independent adverse prognostic factor in patients with resectable gastroesophageal adenocarcinomas with and without neoadjuvant treatment.