Reply to Wentao Liu, Xiaokun Zhao, Zhaohui Zhong's Letter to the Editor re: Marcus G. Cumberbatch, Matteo Rota, James WF Catto, Carlo La Vecchia. The Role of Tobacco Smoke in Bladder and Kidney Carcinogenesis: A Comparison of Exposures and Meta-analysis of Incidence and Mortality Risks. Eur Urol 2016;70:458-66