Marijuana linked to testicular cancer in US study The research is not ironclad proof that the marijuana is to blame, and even if it is, the danger is not overwhelming. According to the American Cancer Society, a man's lifetime risk of getting testicular cancer is about one in 270 - and because effective treatment is available, the risk of dying from the disease is just one in 5,000. Cortessis and her colleagues used data from 163 young men who had been diagnosed with testicular cancer and nearly 300 men in a comparison group without the disease. Both groups had been interviewed about their health and drug use between 1987 and 1994. Among the men with cancer, 81 per cent had used marijuana at some point, whereas that was the case for 70 per cent of the comparison group. By contrast, cocaine use was linked to a smaller risk of the tumours. The new study is "interesting," said Carl van Walraven of the University of Ottawa in Canada, who has studied testicular cancer, but said it has a number of limitations. For instance, it did not find an increased risk among men with higher marijuana use, and it was relatively small. But Cortessis highlighted the consistent results from all the studies so far. It is hard to imagine a scenario whereby it is due to chance and I can't think of a systematic bias that would cause this. I will feel very confident that this is cause and effect once we have worked out the biology," she said.