High systemic immune–inflammation index represents an unfavorable prognosis of malignant pleural mesothelioma

Background: Malignant pleural mesothelioma (MPM) represents a fatal disease with high aggressiveness, and limited biomarkers have yet been identified for MPM. The present study aims to explore potential serum prognostic factors of MPM. Materials and methods: A retrospective analysis of 97 pathologically diagnosed MPM was performed. The optimal cutoff value of pretreatment systemic immune–inflammation index (SII) was determined by receiver operating characteristic curve. Kaplan–Meier curves and Cox regression analysis were performed to assess the potential prognostic roles of parameters. Results: A total of 59.8% (n=58) patients are male, with a median age of 56.0 years (range 18–77). The optimal cutoff value of SII was 988.6×10(9)/L. High and low SII were found in 44 (45.4%) and 53 (54.6%) patients, respectively. Median survival time for total 97 cases was 18.5 months. The median overall survival for patients with low and high SII was 47.0 and 13.0 months, respectively. The 1-, 2- and 3-year survival rates for patients with low SII were 85.8%, 57.8% and 52.0% compared to that of 53.9%, 23.6% and 13.8% in patients with high SII. On univariate analysis, Eastern Cooperative Oncology Group performance status (ECOG PS)<2 points, low SII and adjuvant treatment (P<0.05) were found to be closely correlated with a better prognosis of MPM. Only ECOG PS (P=0.036) and SII (P=0.009) held statistical significance on multivariate analysis. Conclusion: Pretreatment SII is easy to access to, and it represents an efficiency and noninvasive biomarker of MPM. High SII represents an unfavorable independent prognostic factor of MPM, and this needs to be validated in further studies.