By Randy Dotinga
MONDAY, Sept. 10 (HealthDay News) -- A new study suggests that young men with a particularly severe type of testicular cancer are more likely to have smoked pot.
But the findings aren't conclusive and a marijuana researcher questioned their value.
Even if there is a doubled risk for pot smokers, as the study seems to indicate, the overall chances of a young man developing testicular cancer would still be very low, experts said.
However, "young men are entitled to this information so that they can make informed decisions," said study co-author Victoria Cortessis, an assistant professor of preventive medicine at the University of Southern California, in Los Angeles. She said that although the study doesn't prove a cause-and-effect link between marijuana use and testicular cancer, other research has produced similar results.
Testicular cancer is extremely rare, and largely a disease of young men. It is diagnosed in about 8,600 men a year, according to an American Cancer Society estimate, and kills only about 360 since treatment is usually successful. A man's chances of developing the disease over a lifetime are about one in 270.
The new study examined 163 patients who were diagnosed with the most common type of testicular cancer. They were diagnosed between 1986 and 1991 in Los Angeles, and researchers asked about their drug use during in-person interviews.
The researchers compared them to 292 healthy men of similar races, ages and ethnicities.
The study found that of the men with testicular cancer who answered questions about marijuana use, 81 percent had tried the drug. Of the healthy men, 76 percent had tried marijuana.
When researchers looked at an especially severe kind of testicular cancer known as nonseminoma and mixed germ cell tumors, which affected nearly half of the patients, they found that 85 percent had tried marijuana. Only 75 percent of the healthy men had used it.
Compared to those who had never used marijuana, the risk of getting testicular cancer grew after researchers adjusted their findings so they wouldn't be thrown off by factors such as high or low numbers of men of certain ages, races and education levels. The design of the study didn't allow researchers to specify the exact likelihood that young men who use marijuana would get testicular cancer; it only says the risk is higher.
The study also looked at cocaine users, who turned out to have a lower risk of getting the more severe kind of testicular cancer. Forty-three percent of those with the condition had used cocaine, compared to 44 percent of the healthy men. When researchers adjusted their statistics so they wouldn't be influenced by various factors, however, they found that cocaine could have a protective effect.
The study suggested several ways that the drug may reduce the risk of testicular cancer, such as killing cells in the testicles. Cortessis cautioned in a statement, however, that cocaine could make men infertile.
As for marijuana, Cortessis said it's plausible that a component of pot known as THC causes the severe type of testicular cancer in some men.
Marijuana researcher Dr. Donald Abrams questioned the findings. The rates of testicular cancer in California didn't increase in the 1960s and 1970s when pot use went up, said Abrams, chief of hematology-oncology at San Francisco General Hospital and a professor of clinical medicine at the University of California-San Francisco.
"If there were a true cause-and-effect relationship, one would see blips in testicular cancer rates associated with greater use of cannabis," he said.
The study appears online Sept. 10 in the journal Cancer.
For more on testicular cancer, try the U.S. National Library of Medicine.
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