Smokers have much higher odds of developing bladder cancer than previously believed, and the changing makeup of cigarettes might be a factor, new research shows. While cigarettes are more typically associated with lung cancer, researchers have known for years that smoking also raises the risk of bladder cancer. Previous studies of people who smoked before the 1990s had put the risk for smokers at about three times the risk seen among nonsmokers.
But in a new study, published in The Journal of the American Medical Association, a team of scientists at the National Cancer Institute used a larger population group and more recent data, following half a million people between 1995 and 2006. They found that current smokers were four times as likely to develop bladder cancer compared with people who had never smoked, and former smokers had 2.2 times the risk.
The researchers speculate that the larger risk might be a reflection of the more toxic chemicals added to cigarettes. Many cigarette makers have cut back on tar and nicotine in recent years, but replaced them with substances such as beta-naphthylamine, which is known to raise the risk of bladder cancer.
That could explain, at least in part, why bladder cancer rates have remained steady over the years even as the number of smokers has dropped.