Swaminathan and Hatcher showed the role of XO inactivation of the carcinogenesis pathway in bladder cancer (Swaminathan and Hatcher, 1986), and Kono et al., (2012) reported an increased expression in mRNA xanthine dehydrogenase (consequently, XO) along with increased malignancy and decreased survival in the adenocarcinoma of the lung. Here, XDH is linked to urinary bladder cancer.