The aim of this study was to systematically review all evidence evaluating obesity as a prognostic factor for PC mortality. Cohort and case-control studies reporting mortality among PC patients stratified by body mass index (BMI) were included. The risk of mortality among obese patients (BMI ≥ 30) was compared with the risk for normal weight (BMI < 25) patients, pooling individual hazard ratios (HR) in random-effects meta-analyses. Reasons for heterogeneity were assessed in subgroup analyses. Dose-response associations for BMI per 5 kg/m2 change were assessed. Among 7278 citations, 59 studies (280,199 patients) met inclusion criteria. Obesity was associated with increased PC-specific mortality (HR: 1.19, 95% CI: 1.10-1.28, I2: 44.4%) and all-cause mortality (HR: 1.09, 95% CI: 1.00-1.18, I2: 43.9%). There was a 9% increase (95% CI: 5-12%, I2: 39.4%) in PC-specific mortality and 3% increase (95% CI: 1-5%, I2: 24.3%) in all-cause mortality per 5 kg/m2 increase in BMI. In analyses restricted to the higher quality subgroup (NOS ≥ 8), obesity was associated with increased PC-specific mortality (HR: 1.24, 95% CI: 1.14-1.35, I2: 0.0%) and maintained the dose-response relationship (HR: 1.11 per 5 kg/m2 increase in BMI, 95% CI: 1.07-1.15, I2: 26.6%). Obesity had a moderate, consistent, temporal, and dose-response association with PC mortality. Weight control programs may have a role in improving PC survival.
Keywords: all-cause mortality; body mass index; causation; outcomes; prostate cancer specific mortality.