Does marijuana increase the risk of testicular cancer?

BY: Michael Castleman

Possibly. Researchers at the Fred Hutchinson Cancer Research Center in Seattle recently found that men who smoked marijuana have almost twice the risk of developing nonseminoma, the more aggressive form of testicular cancer, than men who abstained. In addition, the more often a man smoked, the higher his risk: weekly smokers had about twice the risk of nonsmokers, and daily smokers had three times the risk. Finally, compared with men who started smoking marijuana after age 18, those who started before 18 had twice the risk of testicular cancer. 

“Incidence of testicular cancer has been rising in the U.S. and Europe over the last 40 years,” says lead researcher Janet Daling, Ph.D. “Marijuana use has also risen over the same period. It seemed logical that there might be an association between the two. We found a fairly strong relationship.”

However, an association between marijuana smoking and testicular cancer does not necessarily mean that the former causes the latter. In the U.S., both testicular cancer and marijuana use are most common among affluent white men. It’s possible, however, that it’s not marijuana but some other aspect of an affluent lifestyle that is causing the increase in cancer, notes Gary Schwartz, Ph.D., an associate professor of cancer biology and epidemiology at Wake Forest University in Winston-Salem, N.C.

Experts agree that more research needs to be done. In the meantime, “men who smoke marijuana should keep our findings in mind,” advises Daling, especially if you have risk factors for testicular cancer, which include an undescended testicle, a family history of the disease, HIV infection or being white or between the ages of 20 and 54.