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FRIDAY, Feb. 3 (HealthDay News) -- Smoking marijuana may raise the risk for bladder cancer occurring relatively early in life, new research shows.


"We noticed several younger patients who had developed transitional cell carcinoma were similar in that they all shared a history of marijuana smoking," senior study author and urologist Dr. Martha Terris, of the Medical College of Georgia in Augusta, said in a prepared statement.

Her team's study of 52 men, aged 44 to 60, with transitional cell bladder cancer found that 88.5 percent of them had a history of smoking marijuana. Nearly 31 percent still smoked marijuana at the time of the study.

"The literature has suggested that marijuana smoking increases the risk of head and neck cancer and lung malignancies, and that these tumors tend to develop earlier and behave more aggressively in marijuana smokers," Terris noted.

Cigarette smoking is a major risk factor for bladder cancer. This study suggests that smoking marijuana may be as bad or worse a risk factor.

"Marijuana smoking might be an even more potent stimulator of malignant transformation in transitional epithelium [bladder lining] than tobacco smoking," the study authors wrote.

The researchers noted that marijuana metabolites have a half-life in urine about five times greater than nicotine metabolites. This means that THC, the main psychoactive ingredient in marijuana, stays in the bladder and urine for a long time. THC has been found to have both anti-tumor and tumor-producing properties.

The study was published in the January issue of Urology.

Terris suggested that when a doctor detects blood in a young patient's urine sample, the doctor should ask the patient about his or her marijuana use, and more strongly consider bladder cancer as a cause of the blood in the urine.

Bladder cancer patients may also want to reconsider the use of marijuana to treat the side effects of chemotherapy, she said.

"If they are getting chemotherapy for their bladder cancer and smoking marijuana to increase their appetite, they may be undoing the benefits of chemotherapy," Terris said.

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Her team's study of 52 men, aged 44 to 60, with transitional cell bladder cancer found that 88.5 percent of them had a history of smoking marijuana. Nearly 31 percent still smoked marijuana at the time of the study.

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