Apr. 4, 2001 Los Angeles, April 3, 2001 — Cigarette for cigarette, smoking appears to pack a bigger punch for women than men when it comes to bladder cancer risk, according to a new study led by preventive medicine researchers at the Keck School of Medicine of the University of Southern California.
As a whole, cigarette smokers were found to run 2.5 times the risk of contracting bladder cancer than nonsmokers; but within this increased risk due to smoking, women appear to face an even greater risk than men, according to the report in the April 4 issue of the Journal of the National Cancer Institute.
"Our large, case-control study provides the first evidence, to our knowledge, that when comparable numbers of cigarettes are smoked, the risk of bladder cancer is higher in women than in men," said J. Esteban Castelao, researcher in preventive medicine and lead author of the study.
Castelao and colleagues at USC and the Massachusetts Institute of Technology conducted the epidemiological study among 1,514 patients with bladder cancer and 1,514 other comparable study participants in the Los Angeles area. Researchers asked about general smoking habits, how many cigarettes participants smoked and how often, as well as which types of cigarettes they smoked and how they inhaled (deeply, moderately or lightly).
For both genders, the risk of bladder cancer appeared to rise both with the number of cigarettes smoked each day and with the number of years that participants had smoked regularly. In nearly every category of smoking, however, the risks to women were greater than those to men.
Women who smoked 40 or more cigarettes a day for 40 years or more, for example, faced more than twice the risk of contracting bladder cancer as men with the same smoking habit. These women incurred more than 11 times the risk of bladder cancer than a non-smoker, while men ran approximately five times the risk of a non-smoker.
The researchers also analyzed blood samples from 1,363 study participants, looking for evidence of exposure to arylamines, chemicals in cigarette smoke known to cause bladder cancer. They found that among men and women who smoked at the same level, concentrations of 3- and 4-aminobiphenyl hemoglobin adducts in the blood—markers of arylamine exposure and indices of their carcinogenic potential —were higher in women than in men.
When comparing types of cigarettes, researchers found no difference in bladder cancer risk associated with filtered versus unfiltered cigarettes or low-tar versus high-tar cigarettes—nor any difference in risk tied to whether smokers reported deep or shallow inhalations.
Bladder cancer currently accounts for 6 percent of all new cancer cases in men and 2 percent of all new cancer cases in women. The American Cancer Society estimates that 53,200 Americans were diagnosed with the cancer and 12,200 Americans died from it in 2000. About half of all cases are believed to be caused by smoking.
The authors also noted that growing evidence also indicates that when smoking levels are equal, women incur a higher risk of lung cancer than men. Research was funded through grants by the National Cancer Institute and the National Institute of Environmental Health Sciences.
J. Esteban Castelao, Jian-Min Yuan, Paul L. Skipper, Steven R. Tannenbaum, Manuela Gago-Dominguez, J. Slade Crowder, Ronald K. Ross and Mimi C. Yu, Gender- and Smoking-Related Bladder Cancer Risk. Journal of the National Cancer Institute, Vol 93, No. 7, April 4, 2001.
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