Maybe it is not as safe as everyone claims.

Marijuana Use Tied to Testicular Cancer Risk

By KATIE MOISSE

Young men who use marijuana have a higher risk of testicular cancer, a new study found.

The study of 455 Californian men found those who had smoked pot were twice as likely to have been diagnosed with testicular germ cell tumors, the most common form of testicular cancer in men younger than 35.

"Testicular cancer is on the rise," said study author Victoria Cortessis, assistant professor of preventive medicine at the University of Southern California's Keck School of Medicine in Los Angeles. "So we asked, 'What is it that young men are doing more frequently that could account for the increased risk?'"

Cortessis and colleagues used interviews to probe recreational drug use among 163 men diagnosed with testicular cancer and 292 healthy men of the same age, and found those who smoked marijuana had double the risk of testicular tumors compared with men who passed on grass. On top of that, their tumors tended to be faster-growing and tougher to treat.

"Most men who get testicular cancer today survive, and that's wonderful. But as a result of treatment, they may have problems with fertility or sexual function," said Cortessis. "So we're talking about the risk of developing the cancer in the first place as well as the subsequent effects of the cancer and its treatment."

"We now have three studies connecting marijuana use to testicular cancer, and no studies that contradict them," said Stephen Schwartz, an epidemiologist at the Fred Hutchinson Cancer Center in Seattle and author of the first study linking marijuana use to testicular cancer in 2009. "I think we should start taking notice."

The National Cancer Institute estimates more than 8,500 men will be diagnosed with testicular cancer in 2012. About 360 of them will die from it.

But how marijuana affects the risk of testicular cancer is unclear. In animal studies, marijuana smoke and the cannabis chemical tetrahydrocannabinol, or THC, reduce levels of circulating hormones like testosterone.

"We know testosterone is an important regulator of testes development and function," said Cortessis. "It may be that marijuana use disrupts this regulation in a way that makes the testes much more vulnerable to cancer."

Cortessis suspects boys who experiment with marijuana during puberty might be particularly susceptible. In her study, the risk of testicular cancer was higher among men who smoked less than once a week and for fewer than 10 years.

"Guys who tried it and abandoned it may have been very young," she said, adding that her study was too small to tease out age-related risks. "We plan to investigate the possibility that men who use marijuana during puberty may be especially vulnerable, which makes sense if marijuana is disrupting the hormone signaling that directs the testes to maturity."

But other factors could be at play, as men who use marijuana are more likely to drink and use other drugs. However, Cortessis found men who used cocaine were actually less likely to develop testicular cancer – a result that might reflect the drug's toxic effects.

"My suspicion is that the effect of cocaine is to kill the germ cells so they're not there," she said, describing how cocaine cuts testicular size and function in mice. "It's more analogous to a mastectomy to reduce the risk of breast cancer. And for a young guy, that would be high price to pay."

Cortessis and Schwartz agree more work is needed to uncover how marijuana use affects testicular cancer risk, but said men "shouldn't assume smoking marijuana has no impact on your health," according to Schwartz.

"I think at this stage of knowledge men deserve to be informed of this," said Cortessis. "It's not a huge body of work, but the results are so consistent that it's very unlikely this is due to chance."

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Here's what I don't like about these kinds of reports on these studies...


So I'm thinking they do about 50% that smoke pot, and 50% that don't? So about 230 on either side.


So this is saying across the board - including older than 35 years old - they see about 8.5k that are diagnosed per year. So over 20 years, you are seeing 170,000 cases (in the US?) Out of 170 million males (approx) for a total of 0.001% chance? And they've been able to determine that they are twice as likely to get it which means you have at least three guys with cancer out of the 455?

Well, apparently, they don't do the study that way -- they pull people that already have testicular cancer (163 of them) and pull people that don't have testicular cancer (292) and then see what they smoked. And then this expert goes on to say it could be due to other lifestyle habits that those that smoke pot tend to do as opposed to those who don't, and that there really isn't sufficient analysis on the whole thing in general. But he thinks it is important to note... and the expert is the one who administered the first study (and is looking for credit for establishing this connection - a connection which he admits is not conclusive.)

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