Abstract
Despite that immune checkpoint inhibitors (ICIs) had tremendous improved the survival of multiple solid tumors, only a limited proportion of patients are responsive to ICIs. Therefore, effective variables are urgently needed to predict the probability of response to ICIs. Systematic searches were conducted from inception up to May, 2020. Prospective or retrospective studies of ICIs that investigated the association between body mass index (BMI) and survival outcomes, including overall survival (OS) and/or progression-free survival (PFS), were selected. The association between each BMI category and survival outcomes was calculated using Cox proportional hazard regression models and quantified as hazard ratio (HR) with corresponding 95% confidence interval. Seven clinical studies involving data from 3768 individual patients were included. The median OS was 15.5 months (95% confidence interval: 14.7-16.2 mo) and the median PFS was 5.7 months (5.2-6.3 mo). The median OS was significantly longer in overweight/obese patients than in nonoverweight patients (20.7 vs. 11.3 mo; P<0.001). The difference in OS between overweight and obese patients was not statistically significant (HR: 1.14, P=0.098). Similar results were observed for PFS outcomes. Subgroup analysis demonstrated improved OS in overweight/obese patients with nonsmall-cell lung cancer (HR: 0.81, P=0.002), melanoma (HR: 0.66, P<0.001), renal cell carcinoma (HR: 0.53, P<0.001), and multiple cancer type (HR: 0.34, P<0.001), with parallel results noted regarding PFS outcomes. Results of the present study suggested that BMI may be a satisfactory prognostic factor for patients treated with ICIs.