Obesity and risk of bladder cancer: A meta-analysis of cohort studies

Abstract

Objective: Previous epidemiologic studies demonstrated that obesity might associated with the risk of bladder cancer. However, many of the actual association findings remained conflicting. To better clarify and provide a comprehensive summary of the correlation between obesity and bladder cancer risk, we conducted a meta-analysisto summarize results of studies on the issue. Stratified analyses were also performed on potential variables andcharacteristics. Methods: Studies were identified by searching in PubMed and Wanfang databases, covering all thepapers published from their inception to March 10, 2013. Summary relative risks (SRRs) with their corresponding 95% confidence intervals (CIs) were calculated by either random-effect or fixed-effect models. Results: A total of 11 cohort studies were included in our meta-analysis, which showed that obesity was associated with an increased risk for bladder cancer in all subjects (RR=1.10, 95% CI=1.06-1.16; p=0.215 for heterogeneity; I2=24.0%). Among the 9 studies that controlled for cigarette smoking, the pooled RR was 1.09 (95% CI 1.01-1.17; p=0.131 for heterogeneity; I2=35.9%). No significant publication bias was detected (p = 0.244 for Egger's regression asymmetry test). Conclusions: Our results support the conclusion that obesity is associated with the increased risk of bladder cancer. Further research is needed to generate a better understanding of the correlation and to provide more convincing evidence for clinical intervention in the prevention evention of bladder cancer.