摘要： The clinical benefit of PDD-assisted TURBT with 5-ALA is evident from several studies.1–3 We carried out a phase III study of this new diagnostic technique in Japan using a preoperative oral administration of 20 mg/kg 5-ALA.2 On the basis of the reported high diagnostic accuracy and good safety profile, oral 5-ALA has been approved as an intraoperative diagnostic drug in Japan since December 2017. The toxicity induced by 5-ALA is reported to be low, because 5-ALA is a non-fluorescent natural amino acid produced by the mitochondria in animals and plants.3,4 However, 5-ALA administered into the body is predominantly incorporated by the liver, kidney, muscle and malignant tumor tissue, and metabolized to protoporphyrin IX in a heme synthetic pathway.5,6 Administration of 5-ALA is associated with a potential risk of liver toxicity as a result of the substantial accumulation of its metabolites.6,7 Although evidence regarding its liver toxicity has been reported in Europe and the USA, such data are significantly lacking for Japanese patients. In the present study, we systematically evaluated liver parameter reactions in patients with bladder cancer who underwent 5-ALA-mediated PDD-TURBT to recommend the routine surveillance required in the regular clinical setting.