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Study Suggests Cannabis Use May Lower The Risk of Bladder Cancer

San Diego, CA, May 5, 2013- While research shows cigarette smoking is the greatest risk factor for bladder cancer, a new study being presented at the 108th Annual Meeting of the American Urological Association indicates smoking marijuana (cannabis) may lower the risk of bladder cancer.The study will be presented to reporters during a special press conference at the San Diego Convention Center, San Diego, CA on Monday, May 6 at 8:30 a.m. PT.

Nearly 40,000 multi-ethnic men between 45-69 years of age were evaluated as part of the study, which was conducted by Kaiser Permanente, Los Angeles, CA. Mailed questionnaires were utilized to collect information on demographic and lifestyle factors, including smoking history and cannabis use. Researchers then compared these data points with clinical records, including cancer data from electronic health records. Cox models were used to assess bladder cancer risk in patients who smoked tobacco, cannabis or both.

Data analyses revealed more than 14,500 patients used marijuana, 21,770 smoked cigarettes and 10,027 used both. Of the categories, cigarette smokers were found to have a higher risk of bladder cancer than cannabis smokers (hazard ratio of 1.38 vs. 0.38).

“This study suggests men who use marijuana or a combination of marijuana and cigarettes are still less likely to develop bladder cancer than those who smoke only cigarettes,” said Jeff Holzbeierlein, MD, Director of Urologic Oncology, University of Kansas Medical Center. “With the many debates over the use and legalization of marijuana for medicinal purposes, additional research is needed to understand this observation and its potential relationship to bladder cancer in smokers.”

Bladder cancer is the sixth most common cancer in the United States. For 2013, it is estimated 72,570 Americans will be diagnosed with bladder cancer and 15,210 will die of the disease. 

NOTE TO REPORTERS: Experts are available to discuss this study outside normal briefing times. To arrange an interview with an expert, please contact the AUA Communications Office at the number above or e-mail

About the American Urological Association: Founded in 1902 and headquartered near Baltimore, Maryland, the American Urological Association is a leading advocate for the specialty of urology, and has more than 19,000 members throughout the world. The AUA is a premier urologic association, providing invaluable support to the urologic community as it pursues its mission of fostering the highest standards of urologic care through education, research and the formulation of health policy.

Christine Frey, AUA