The prognostic role of obesity is independent of sex in cancer patients treated with immune checkpoint inhibitors: A pooled analysis of 4090 cancer patients

Objective: Recent studies suggest obesity is associated with improved survival of cancer patients treated with immune checkpoint inhibitors (ICIs). We performed this meta-analysis to evaluate the impact of obesity on survival of these patients with regard to the cutoff value of body mass index (BMI) as well as sex. Methods: Electronic databases including Pubmed, Emabse, and the Cochrane library were systematically searched until April 2019, without language limitation. Clinical studies evaluating the association between BMI and survival of cancer patients treated with ICIs were included. The main endpoints were overall survival (OS) and progression-free survival (PFS). Data from individual studies were extracted by two researchers, independently. RevMan 5.3 and Stata 11 software were used to perform the analysis. Results: 16 retrospective studies met the inclusion criteria, with a total of 4090 patients. The OS (HR = 0.72, 95% CI: 0.51-1.02; P = 0.06) and PFS (HR = 0.67, 95% CI: 0.48-0.95; P = 0.02) of the high BMI group were improved compared with the low BMI group. Dose-response analysis showed that the risk of death decreased by 3.6% when the BMI increased every 1 kg/m 2 . Subgroup analysis revealed that BMI > 30 was a reliable value for determining significantly better OS (HR = 0.64; 95%CI: 0.43-0,96; P = 0.03). The prognostic effect of BMI on OS was significant regardless of gender (For male, HR = 0.73, 95% CI: 0.61-0.86; P < 0.01. For female, HR = 0.63, 95% CI: 0.43-0.92; P = 0.02). Conclusions: Obesity is associated with better outcomes in cancer patients treated with ICIs, and this clinical benefit may be independent of sex.