[Studies of tryptophan metabolism in cancer of the urinary bladder]

In 100 patients suffering from urinary bladder cancer (pTA-4, Nx, M0-1, G0-3) we created an oral tryptophan load administering 5 g of L-type tryptophan. Thereafter the amount of both xanthurenic acid and kynurenin was determined quantitatively in the 24-hour urine. 16 patients revealed pathological test results and excretion pattern of tryptophan metabolites via kynurenin were similar to vitamin B6-dependent xanthurenic aciduria both in its homocygotic and heterocygotic pattern. It has not been possible to prove a direct correlation between xanthurenic aciduria and urinary bladder cancer. However, xanthurenic aciduria may be of significance as a risk factor in the etiopathogenesis of urinary bladder cancer.