Urinary Tryptophan Metabolites and Cancer of the Bladder In Humans

Urinary excretion of six aromatic amine metabolites of tryptophan was compared between a group of 30 patients with bladder cancer and a group of 33 controls selected from the general population of the study area. Measurements were based on a single overnight urine specimen collected at home by each subject, without a “loading” dose of L-tryptophan. For each metabolite, both the distribution and the mean amount excreted were nearly identical for cases and controls. The small case-control differences in mean values were virtually unchanged by adjustment for age, sex, and smoking status. Generally, excretion levels were higher for females than for males. Excretion levels also tended to be higher for older than for younger subjects and for smokers compared to nonsmokers. However, most of these differences also were small.