Marijuana use linked to increased risk of testicular cancer

Frequent and/or long-term marijuana use may significantly increase a man's risk of developing the most aggressive type of testicular cancer, according to a study by researchers at Fred Hutchinson Cancer Research Center. The study results were published online Feb. 9 in the journal Cancer.

The researchers found that being a marijuana smoker at the time of diagnosis was associated with a 70 percent increased risk of testicular cancer. The risk was particularly elevated (about twice that of those who never smoked marijuana) for those who used marijuana at least weekly and/or who had long-term exposure to the substance beginning in adolescence.

The results also suggested that the association with marijuana use might be limited to nonseminoma, a fast-growing testicular malignancy that tends to strike early, between ages 20 and 35, and accounts for about 40 percent of all testicular-cancer cases.

Since the 1950s, the incidence of the two main cellular subtypes of testicular cancer, nonseminoma and seminoma - the more common, slower growing kind that strikes men in their 30s and 40s - has increased by 3 percent to 6 percent per year in the U.S., Canada, Europe, Australia and New Zealand. During the same time period, marijuana use in North America, Europe and Australia has risen accordingly, which is one of several factors that led the researchers to hypothesize a potential association.

"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 author Stephen M. Schwartz, M.P.H., Ph.D., 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 (those that eventually make sperm in adulthood) fail to develop properly and become vulnerable to malignancy. Later, during adolescence and adulthood, it is thought that exposure to male sex hormones coaxes these cells to become cancerous.

"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, Ph.D., 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."

Chronic marijuana exposure has multiple adverse effects on the endocrine and reproductive systems, primarily decreased sperm quality. Other possible effects include decreased testosterone and male impotency. Because male infertility and poor semen quality also have been linked to an increased risk of testicular cancer, this further reinforced the researchers' hypothesis that marijuana use may be a risk factor for the disease.

Daling first got the idea to explore a possible association between marijuana use and testicular cancer about eight years ago, when she attended a talk by a physician at the University of Washington who presented findings that only two organs, the brain and the testes, had receptors for tetrahydrocannabinol, or THC, the main psychoactive component of marijuana. Since then, a number of other sites have been found to contain THC receptors, including the heart, uterus, spleen and immune-system cells.

The male reproductive system also naturally produces a cannabinoid-like chemical that is thought to have a protective effect against cancer. The authors speculate that marijuana use may disrupt this anti-tumor effect, which could be another explanation for the possible link between marijuana and increased risk of testicular cancer.

For the population-based, case-control study, Daling, Schwartz and colleagues interviewed 369 Seattle-Puget Sound-area men, ages 18 to 44, who had been diagnosed with testicular cancer about their history of marijuana use. For comparison purposes they also assessed marijuana use among 979 randomly selected age- and geography-matched healthy controls. (More than 90 percent of the cases and 80 percent of the controls in the study were Hispanic or non-Hispanic white men, due to the fact that testicular cancer is very rare in African-Americans, and because the Seattle-Puget Sound region has a relatively small African-American population.)

Study participants were also asked about other habits that may be correlated with marijuana use, including smoking and alcohol consumption. Even after statistically controlling for these lifestyle factors, as well as other risk factors, such as first-degree family history of testicular cancer and a history of undescended testes, marijuana use emerged as a significant, independent risk factor for testicular cancer.

The researchers emphasize that their results are not definitive, but rather open a door to more research questions.

"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, such as why marijuana appears to be associated with only one type of testicular cancer. "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," he said.

In future studies the researchers plan to measure the expression of cannabinoid receptors in both seminomatous and nonseminomatous tumor tissue from the cases in the study, and to see whether variation in the genes for the receptors and other molecules involved in cannabinoid signaling influences the risk of testicular cancer.

In the meantime, Schwartz said, "What young men should know is that 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," he said. "So, in the absence of more certain information, a decision to smoke marijuana recreationally means that one is taking a chance on one's future health."

Source: Fred Hutchinson Cancer Research Center

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Marijuana use may increase risk of testicular cancer: study

Citation: Marijuana use linked to increased risk of testicular cancer (2009, February 9) retrieved 26 May 2019 from
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Feb 09, 2009

Feb 09, 2009
I believe smoking was linked to causing cancers ages ago. I doubt smoking marijuana is any worse for ur nutts than smoking tobacco/opium/straw!

I for one would prefer to get Testicular cancer than any other (more deadly) form so I may up my cannabis intake after reading this.

Feb 09, 2009
This article made me lol.

Feb 09, 2009
LuckyBrandon: It might be over-hyping, but the fact we have THC in our cells and that marijuana doesn't contain chemical additives do not mean that smoking it will not possibly increase your chances of getting lung or some other type of cancer.

Also, cigars might not cause lung cancer, but they do cause, or increase the risk of mouth and throat cancer, so I wouldn't go puffin the dragon too often.

Personally I'd rather eat mushrooms or spacecake rather than smoke it. Seems like a much safer way to get a high and some say if cooked properly, will get you the same effect. Plus you won't get the munchies afterwards or hey, if you do, eat more spacecake.

Looking at the current flow of news that seems to come in dual opposing pairs, one week you get cancer from something, the other you don't, it's becoming all the more increasingly obvious that we know pretty much jack shit about what triggers cancer and subsequently what will increase your risk of getting it, and what type of cancer you're more likely to get.

We're going to reach a point where the public will have no idea whatsoever if something does or does not cause cancer.

I'm also really unconvinced of whether this type of study actually takes other environmental factors into account, other than the one the study focuses on. For example I'd bet that a lot of those that smoke marijuana might drink Coke, or eat cake, does that mean Coke and cake cause testicular cancer?

There's plenty of reasons why the cannabis sativa plant should be legalized, and I don't think getting high is the most important.

Feb 09, 2009
What the article doesn't report is the incidence of getting testicular cancer -I looked it up and it is around 6 per 100,000 population annually. The odds of dying in a motor vehicle accident are 1 in 6500 annually. Pick yer poison! The chances of dying eventually are 100%.

Feb 10, 2009
My basic questions are : Who are these people and who pays for their research???????

Who benefits?

Since the US struck down the laws that required truth in newspapers and then there are no penalties for direct and knowingly lying in print or any other media..and since over 85% of investigative journalists have been fired or run out of the country..and when an article that agrees with the owners of the given rag may be repeated in perfection (direct full copy) with zero changes or investigation of it's origins by over 3000 news reporting places...

then...where lies truth and integrity??

Question the source, question the message, and question the reasons behind it.

Feb 10, 2009
What is being pointed out here by various readers in more or less cogent ways is that correlation is a very treacherous means of ascertaining anything, especially in a study this small. A 3-6% increase in something that has a "normal" occurrence of only 6 in 100,000 means that, relative to life style and a million other factors, this is insignificant. It certainly does not merit the final line of the article where they say that young men should consider this when deciding whether to use marijuana. Think for a moment of all the other possible consequences of using a drug that lowers inhibitions and reduces coordination. Certainly, having sex or sliding behind the wheel of a car in such a state completely submerge this tiny effect, if the effect is even true. Then, of course, we have the many known and much larger effects of drinking alcohol, which is the other choice that most of these young men are likely to consider. Trying to disambiguate these factors at this level is virtually impossible, so why don't we wait for actual causal research that should result from this correlative finding. When someone comes up with one of these questionable findings, the question that then arises in my mind is, "what is causing the other 94-97% of the cases in marijuana smokers and the 100% of cases in non-marijuana smokers. The question then points to the motivation of the researchers, who really don't care a whit about those who might suffer from testicular cancer, but obviously do care to demonize the smoking of marijuana. With that kind of underlying motivation, trusting correlative research from such seems a stretch. The only present purpose that I can see for this questionable research is another headline in next month's "Readers Digest", the publishers of more such bogus research than the rest of the industry combined.

By the way, this does not make me a proponent of smoking marijuana, just an opponent of bad science used for ideological purposes.

Feb 10, 2009
According to my research, smoking dope increases your chances of contracting up to eight gold medals.

Feb 10, 2009
..and composing excellent music

Feb 10, 2009
... and creating popular travel documentaries on PBS.

Feb 10, 2009
My brother, a long time user of the killer weed, had testicular cancer. This is anacdotal, but still worth telling him about.

Feb 11, 2009
I've got the grant forms filled out pack your bags, We are going to Bangkok, you bring the smokes.

Mar 21, 2009
They should stop studying people who smoke pot that's been sprayed with gov. pesticides.

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