Role of Urinary β-Glucuronidase in Human Bladder Cancer¹

It has been suggested that high levels of urinary β-glucuronidase may increase an individual's risk of bladder cancer by releasing free carcinogens from their inactive glucuronide conjugates in the bladder. The hypothesis derives in part from the high levels of urinary β-glucuronidase observed in bladder cancer patients. Because most of the individual variation in levels of urinary β-glucuronidase and other lysosomal enzymes in the normal population is genetically determined, we would expect that, if high glucuronidase levels were a predisposing factor in the disease, bladder cancer patients would transmit this trait to their progeny. We have tested this hypothesis and find that levels of urinary β-glucuronidase and three other lysosomal enzymes, α-galactosidase, β-galactosidase, and β-hexosaminidase, are not significantly elevated in 34 progeny of bladder cancer patients compared to 34 matched controls. Additionally, 15 bladder cancer patients judged to be disease free for a median time of 5 years did not have elevated levels of urinary β-glucuronidase when compared to a normal population of 125 individuals. Thus, the high levels of glucuronidase observed in bladder cancer patients are most likely a consequence of disease rather than a cause.