Background:Renal transplantation has been associated with a significantly increased risk of developing cancers during long-term follow-up, but for bladder cancer, this risk is less clear. We therefore performed a meta-analysis to determine whether bladder cancer risk in renal transplant recipients was increased.Methods:Eligible studies were identified through searches of PubMed and other public resources. Random-effects meta-analyses were used to pool overall estimates for standardised incidence ratios (SIRs). Heterogeneity test, sensitivity analysis, and assessment of publishing bias were also performed.Results:We identified a 3.18-fold higher SIR (95% confidence intervals (CI): 1.34–7.53, P=0.008) of bladder cancer in patients following renal transplantation compared with the general population, based on data from 79 988 patients with a total follow-up of 308 458 patient-years. When stratified by ethnicity, the SIRs for bladder cancer were 2.00 (95% CI: 1.51–2.65, P=0.001) and 14.74 (95% CI: 3.66–59.35, P<0.001) between European and Asian renal transplant recipients, respectively.Conclusions:Our study demonstrated that the risk of developing bladder cancer in transplant populations was increased. Such association suggests that physicians should be more vigilant in checking for bladder cancer in transplantation recipient population.

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