4:50pm

Tue August 16, 2011
Shots - Health Blog

As More Women Smoke, Their Risk of Bladder Cancer Grows

Smoking rates have dropped over the last several years, but they now seem to be stuck at about 20 percent for the nation. And nearly as many women now smoke as men, according to the Centers for Disease Control and Prevention.

Meanwhile, bladder cancer rates haven't gone down much in the last 30 years. While experts have known for a long time that cigarette smoking is a main cause of bladder cancer, they thought for a while that women were less likely than men to get it from smoking. But a new analysis, published Tuesday in the Journal of the American Medical Association, found that women smokers are just as vulnerable to bladder cancer as men.

The scientists from the National Cancer Institute who authored the study say they think they know why: More women are smoking, and cigarettes have become more deadly.

People who smoke are four times as likely to suffer bladder cancer than are non-smokers. The disease kills 15,000 Americans each year.

"Previous studies were done at a time when women didn't smoke as much as men," Neal Freedman, an investigator at NCI's division of cancer epidemiology and genetics, told Shots. Today, alas, that's changed. Freedman thinks that's why the cancer risk for men and women is now the same.

Changes in the chemical composition of cigarettes may have played a role, too. Starting in the 1950s, as evidence mounted showing that tobacco caused cancer, tobacco companies started rejiggering cigarettes to reduce the amount of tar and nicotine delivered in a puff. But those "light" cigarettes turned out to be no less dangerous than regular cigarettes. That could be because smokers inhaled more, or because the amount of other cancer-causing chemicals, such as nitrosamines, increased.

Marketing of "light" cigarettes was banned last year. But many smokers still think, wrongly, that they are somehow safer.

There are thousands of chemicals in tobacco smoke. Hundreds of those, including arsenic and benzene, are toxic, and at least 70 cause cancer. A report last year from Surgeon General Regina Benjamin summed up the current thinking on why tobacco is so toxic: Smoking causes immediate cellular damage, and continued smoking cripples the body's ability to repair that damage.

Tobacco smoke causes 50 percent of bladder cancers, and 85 percent of lung cancers in the United States. It is implicated in one in three cancer deaths. Plenty of reasons, Freedman says, for women (and men) to never pick up the habit, or to quit now.

Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.