The predictive value of body mass index on prognosis and adverse events of cancers treated with immunotherapy: a systematic review and meta-analysis

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.