February 9, 2009

Marijuana Use Linked To Testicular Cancer Risk

Long-term marijuana use may be linked to an increased risk of developing the most aggressive form of testicular cancer, US researchers reported on Monday.

The team studied 369 Seattle-area men with testicular cancer who ranged in ages from 18 to 44 along with 979 men in of similar age who did not have testicular cancer.

They found that those who currently smoke pot are 70 percent more likely to develop testicular cancer than those who do not.

The risk was heightened among men who had reported smoking marijuana for at least 10 years, used it more than once a week, or started using it before age 18, said Stephen Schwartz and colleagues from the Fred Hutchinson Cancer Research Center in Seattle.

"Our study is not the first to suggest that some aspect of a man's lifestyle or environment is a risk factor for testicular cancer, but it is the first that has looked at marijuana use," said Schwartz, an epidemiologist and member of the Public Health Sciences Division at the Hutchinson Center.

Established risk factors for testicular cancer include a family history of the disease, undescended testes and abnormal testicular development. The disease is thought to begin in the womb, when some fetal germ cells fail to develop properly and become vulnerable to malignancy.

"Just as the changing hormonal environment of adolescence and adulthood can trigger undifferentiated fetal germ cells to become cancerous, it has been suggested that puberty is a 'window of opportunity' during which lifestyle or environmental factors also can increase the risk of testicular cancer," said senior author Janet R. Daling, an epidemiologist who is also a member of the Center's Public Health Sciences Division.

"This is consistent with the study's findings that the elevated risk of nonseminoma-type testicular cancer in particular was associated with marijuana use prior to age 18."

Testicular cancer is among the most common cancers in younger men. About 8,000 men in the United States are diagnosed with testicular cancer per year, and there are about 140,000 U.S. men alive who have survived the disease, the group said.

Incidence in Europe and North America is far higher than in some other parts of the world, and has been rising steadily for no apparent reason, according to BBC News.

"What young men should know is first, we know very little about the long-term health consequences of marijuana smoking, especially heavy marijuana smoking, and second, our study provides some evidence that testicular cancer could be one adverse consequence," said Schwartz, who said the next step in research would be to determine if any of the testicular cells had receptors set up to respond to cannabis chemicals.

"Our study is the first inkling that marijuana use may be associated with testicular cancer, and we still have a lot of unanswered questions," Schwartz said.

"We need to conduct additional research to see whether the association can be observed in other populations, and whether measurement of molecular markers connected to the pathways through which marijuana could influence testicular cancer development helps clarify any association that exists."


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