Current cigarette smokers have a higher risk of bladder cancer than previously reported, and the risk in women is now comparable to that in men, according to a study by scientists from the National Cancer Institute (NCI), part of the National Institutes of Health. The report was published on Aug. 16, 2011, in the Journal of the American Medical Association.

This latest study uses data from over 450,000 participants in the NIH-AARP Diet and Health Study, a questionnaire-based study that was initiated in 1995, with follow-up through the end of 2006.

While previous studies showed that only 20 to 30 percent of bladder cancer cases in women were caused by smoking, these new data indicate that smoking is responsible for about half of female bladder cancer cases – similar to the proportion found in men in current and previous studies. The increase in the proportion of smoking-attributable bladder cancer cases among women may be a result of the increased prevalence of smoking by women, so that men and women are about equally likely to smoke, as observed in the current study and in the U.S. population overall, according to surveillance by the CDC. The majority of the earlier studies were conducted at time periods or in geographic regions where smoking was much less common among women.