According to a new study, smoking marijuana increases a young man’s risk of testicular cancer. Male marijuana smokers were twice as likely to be diagnosed with testicular cancer than men who had never used the drug. The study reviewed data from 163 young men with testicular cancer and 300 men without it. Eighty-one percent of the men diagnosed with cancer had used marijuana at some point between 1987 and 1994, compared to only 70 percent of the comparison group. Marijuana users were twice as likely to develop a kind of tumor that is more dangerous and requires more extensive treatment. The study did not find an increased risk for men with higher marijuana use, and it did not find that cocaine use was linked to a higher risk of tumors. Lead researcher Victoria Cortessis, assistant professor of preventive medicine at the University of Southern California, noted that this is the third study consistently demonstrating the increased risk. The risk for testicular cancer is low, with a lifetime risk of about one in 270, according to the American Cancer Society.