Diabetes mellitus and incidence and mortality of kidney cancer: A meta-analysis

Background: Diabetes is associated with increased risk of a spectrum of cancers, but there are few meta-analyses on the association between diabetes and kidney cancer. We performed a meta-analysis of case-control studies and cohort studies to address the incidence and mortality of kidney cancer in diabetes. Methods: Studies were identified by searching PubMed database and manual assessment of the cited references in the retrieved articles. Study-specific relative risks (RRs) and 95% confidence intervals (CIs) were estimated using a random-effect model. Study quality was assessed using the Newcastle-Ottawa scale. Results: A total of 24 studies were included. We found that diabetes was significantly associated with increased risk of kidney cancer (RR=1.40, 95% CI = 1.16 to 1.69), and the results were consistent between case-control and cohort studies. A slightly stronger positive relation was observed in women (RR = 1.47, 95% CI=1.18 to 1.83) than in men (RR=1.28, 95% CI=1.10 to 1.48). Additional analyses indicated that the increased risk of kidney cancer was independent of alcohol consumption, body mass index (BMI)/obesity and smoking. However, there was no association between diabetes and mortality of kidney cancer (RR=1.12, 95% CI=0.99 to 1.20), without heterogeneity (P = 0.419, I-2 = 1.8%). Conclusions: Diabetes mellitus may increase the risk of kidney cancer in both women and men. (C) 2013 Elsevier Inc. All rights reserved.