Smoking marijuana may increase young men's risk of testicular cancer, a new  study suggests.

In the study, marijuana users were about twice as likely to be diagnosed  with testicular cancer compared to those who had never used  marijuana. The link was particularly strong for the types of testicular cancer  that tend to have a worse prognosis, the researchers said.

The study only found an association, and does not show marijuana use causes testicular cancer. However,  the work is the third study to find such a link, and the results warrant  investigation into whether compounds in marijuana smoke may be carcinogenic to  the testes, the researchers said.

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