Marijuana Use Tied to Testicular Cancer

New research finds an association between smoking marijuana and increased risk of cancer in young men.

Results from a new study funded by the National Cancer Institute and the US Public Health Service has found a link between marijuana use and increased risk of testicular cancer in men.

In fact, the prognosis for men who smoke marijuana recreationally was found to be somewhat worse than average. The results were in agreement with two previous reports that found a potential link between marijuana use and testicular cancer.

Researchers at the University of Southern California analyzed self-reports of recreational drug use in 163 young men who had been diagnosed with testicular cancer. They compared their findings with 292 healthy men of the same age and race/ethnicity.

They found that men who had ever smoked marijuana—even just once—were two times more likely to develop testicular cancer. Marijuana users were more likely to have non-seminoma and mixed germ cell tumors, both subtypes of testicular cancer. Those subtypes are normally found in young men and carry a worse prognosis than the seminoma subtype.

Oddly enough, the researchers found that men who reported cocaine use had a reduced risk of testicular cancer. Why this negative association exists is uncertain, but researchers suggest that based on past animal experiments, cocaine may have germ-cell-killing properties.

But before men worry too much about past or current marijuana use, it’s worth pointing out that the results simply reflect an association between drug use and testicular cancer. In addition, it’s not recommended that men pick up a cocaine habit to reduce their risks of cancer, researchers say. “Although germ cells cannot develop cancer if they are first destroyed, fertility would also be impaired,” researcher Victoria Cortessis said in a statement.

The bottom line, researchers say, is that more research is needed to determine what marijuana triggers in the testes—and that the drug may not be as harmless as some people think.

The full study was published in the journal Cancer