CYP2E1 and urinary bladder carcinoma: However, although recent studies have investigated the association of CYP2E1 gene polymorphisms with bladder cancer risk, the reported results were inconsistent, with some studies reporting that CYP2E1 gene polymorphisms may increase the risk of bladder cancer, but not others.[16–23] Therefore, we systematically reviewed the available literature and performed a meta-analysis to evaluate the association of CYP2E1 gene polymorphisms with bladder cancer risk, which might shed valuable insights on our understanding of the biology of bladder cancer.