Phase III randomised chemoprevention study with selenium on the recurrence of non-invasive urothelial carcinoma. The SELEnium and BLAdder cancer Trial

•The Selenium and Bladder Cancer Trial (SELEBLAT) study was a phase III placebo-controlled, double-blind, randomised clinical trial.•SELEBLAT determined the effect of selenium on recurrence of non-invasive urothelial carcinoma.•In total, 151 and 141 patients were randomised in the selenium and placebo group.•The hazard ratio was 0.85 (95% CI; 0.56–1.29) (p = 0.44) for the intention to treat analysis.•Selenium supplementation does not lower the probability of recurrence in bladder cancer.