Relationship between tryptophan metabolism and heterotopic recurrences of human urinary bladder tumors

In order to investigate the possible relationship between tryptophan metabolism and heterotopic recurrences of human bladder tumors, tryptophan metabolite excretion patterns of 38 patients with low-stage bladder tumors were analyzed before and after the ingestion of L-tryptophan. Periodic cystoscopic examinations were performed after the initial removal of bladder tumors. Among 38 patients, 20 patients had normal tryptophan metabolism, and 18 patients had abnormal tryptophan metabolism. Follow-up studies disclosed that all of 18 patients with abnormal tryptophan metabolism had one or more recurrences within 5 years; however, among 20 patients with normal tryptophan metabolism, 8 patients had no recurrences for 5 years, and 12 patients had recurrences within 5 years. These data suggest that tryptophan metabolites may play a role in heterotopic recurrences of bladder tumors in patients with abnormal tryptophan metabolism and that it might be possible to retard the development of recurrences by correction of tryptophan metabolism in those patients.