Bladder cancer is one of the most common genitourinary cancers and remains challenging to treat because there is a high associated mortality once it has spread outside of the bladder.  The early detection of bladder cancer may confer higher survival rates among patients because the disease may be successfully treated if it is organ confined.  Tobacco smoking is the most significant risk factor for bladder cancer.

Recently,  a study by Anil A. Thomas, M.D., an endourology fellow with the Department of Urology at Kaiser Permanente Los Angeles Medical Center looked into the relationship between cannabis use and bladder cancer.  “We analyzed the records from participants in the California Men’s Health Study, and found that men who reported cannabis use had a significantly lower incidence of developing bladder cancer.  From our results, we do not support the use of cannabis to prevent bladder cancer, but this link needs to be explored further to determine if there are indeed anti-tumoral properties of cannabis that inhibit the development of bladder cancer in select populations.  Future breakthroughs could further our understanding of this complex disease and may eventually lead to new treatments for patients suffering from bladder cancer,” said Dr. Thomas.

Study Results Hold Promise with New Discoveries

The study results were presented at the 2013 A.U.A. meeting and reviewed the incidence of bladder cancer in the California Men’s Health Study which included more than 82,000 multi-ethnic men between 45 to 69 years of age at the Kaiser Permanente Southern California and Kaiser Permanente Northern California. Those with a prior history of bladder cancer were excluded from the study.  The questionnaires queried patients about their quality of life habits, demographics, and lifestyle factors, such as, smoking history and cannabis usage.  The men were followed over an 11-year period and 279 (0.3%) developed incident bladder tumors. 

The results of the study were remarkable.

• Nearly 34,000 (41%) of men reported cannabis use.

•  47,000 plus men reported tobacco use.

Comparative Analysis

• 190 men who did not report cannabis use developed bladder cancer.

•  89 men who reported cannabis use developed bladder cancer.

After adjusting for age, race/ethnicity, and BMI, men who reported only 1-2 times of cannabis use had no reduction in the incidence of bladder cancer, whereas men using cannabis greater than 500 times had a reduction in their bladder cancer hazard ratios.

• A 45% reduction in the risk of bladder cancer was found among men who used cannabis only.

•  A 52% increase in the risk of cancer with tobacco use only (documented previously). 

•  A 28% increase in the risk of cancer with tobacco and cannabis use, demonstrating that cannabis use may decrease the increased risk of bladder cancer in men who smoke tobacco.

The Potion May Be in the Properties

As Dr. Jeff Holzbeierlein of Kansas explains, “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.” For many years, research has demonstrated that properties in Cannabis Sativa (Marijuana) offer anti-tumoral activity. In recent years, select types of Marijuana have been used for the treatment of chronic pain, insomnia, eczema, epilepsy, symptoms of multiple sclerosis and other conditions. 

“Since the cause and effect relationship was not established in this study, I would like to see more studies that can offer quantifiable information to help determine the safety and effectiveness of cannabis use for the prevention of bladder cancer,” said Gary Chien, MD, director, Urology Residency Program and Minimally Invasive Endourology Fellowship, Kaiser Pemanente Los Angeles Medical Center.

It is important to recognize that all information contained on this website cannot be considered to be specific medical diagnosis, medical treatment, or medical advice. As always, you should consult with a physician regarding any medical condition.