Abstract
OBJECTIVE: High body mass index (BMI) greater than 25 kg/m(2) has a complex relationship with cancers. The aim of this systematic review and meta-analysis is to explore controversy over whether BMI is correlated with outcomes including survival and immunotherapy-related adverse events (irAEs) in cancer patients treated with immunotherapy. METHODS: We searched PubMed, Embase, Web of Science, and The Cochrane Library for relevant studies published up to June 2020. Title/abstract screening, full-text review, data extraction, and quality assessment were performed independently. Subgroup analysis was based on sex, treatment lines, the status of programmed death-ligand 1 (PD-L1), and tumor types. Sensitivity analysis was performed by synthesizing studies that adjusted for certain covariates or studies with good quality. Statistical heterogeneity was evaluated by the I(2) value. Meta-analysis was performed with hazard ratio (HR) / odds ratio (OR) and 95% confidence intervals (CIs) as the effect measures. RESULTS: Twenty studies were included for survival and irAEs analyses. Patients with high BMI who underwent immunotherapy had longer overall survival (OS) (pooled hazard ratio, pHR = 0.71 [95% CI: 0.59-0.85]) and progression-free survival (PFS) (pHR = 0.76 [95% CI: 0.65-0.88]) than those with low BMI; at the same time, high-BMI patients had increased irAEs (OR = 2.54 [95% CI: 1.12-5.79]). CONCLUSION: In general, high BMI was correlated with improved OS and PFS in patients treated with immunotherapy along with a high risk of irAEs. However, discrepant findings from subgroup analyses urgently call for further analysis.