Cancer: Smoking & the Bladder

The statistical fact that heavy cigarette smokers are more likely to die of lung cancer than are nonsmokers has been known for years, but no one has yet been able to pinpoint the process by which smoking exerts its lethal effect. That the death rate from cancer of the bladder is more than three times as high for smokers as for nonsmokers has been recognized more recently, and it has seemed even more difficult to explain. Yet, ironically, it is the hard to explain bladder cancers that have backed up statistics by yielding the first biochemical evidence that smoking is a cause of cancer.

Some chemicals once used in dye-making have been clearly shown to cause bladder cancer in both industrial workers and laboratory animals, and last week Dr. William K. Kerr of Toronto's famed Banting Institute reported that he had found similar cancer-causing chemicals in the urine of heavy smokers. The villain in the piece, reported Dr. Kerr and his colleagues at the University of Toronto, is a group called the ortho-aminophenols.

Dr. Kerr's team did 30 special tests on volunteers, some of whom normally smoked but quit for a while during the experiment, some of whom did not smoke but took it up for a while for the sake of science. The results were the same in both groups: men who were using cigarettes excreted in their urine abnormally large amounts of an ortho-aminophenol known to be capable of causing cancer. Going off cigarettes reversed the effect. The researchers' conclusion: inhaling smoke into the lungs, a practice that would seem to have no bearing on cancer of the bladder, is directly related to that disease through the complex chemistry of human metabolism.