"More research needed" over testicular cancer cannabis link
A US study has suggested that the risk of testicular cancer appears to be higher among men who smoke cannabis, particularly those who use the drug regularly or have been smoking it for a long time.
A Cancer Research UK spokesman said that the study was too small to draw firm conclusions.
The US-based researchers asked 369 men between the ages of 18 and 44 who had been diagnosed with testicular cancer, and a further 979 cancer-free men, whether or how often they smoked cannabis, as well as other information about their lifestyle.
- Henry Scowcroft, science information manager, Cancer Research UK
The results suggest that men on the study who smoked cannabis were around 70 per cent more likely to develop testicular cancer than those who had never smoked the drug.
Men who used cannabis at least once per week or had long-term exposure to the drug were around twice as likely to develop testicular cancer.
The risk of testicular cancer was raised, regardless of a man's smoking status, alcohol consumption and family history of the disease.
Study author Dr Stephen Schwartz, an epidemiologist and member of the Public Health Sciences Division at the Hutchinson Centre, commented: "Our study is not the first to suggest that some aspect of a man's lifestyle or environment is a risk factor for testicular cancer, but it is the first that has looked at marijuana use.
"We need to conduct additional research to see whether the association can be observed in other populations, and whether measurement of molecular markers connected to the pathways through which marijuana could influence testicular cancer development helps clarify any association that exists."
Henry Scowcroft, science information manager at Cancer Research UK, said: "As the researchers themselves point out, this is the first inkling that there is any association between chronic marijuana use and testicular cancer. But the researchers only interviewed a relatively small number of men.
"So before we can reach any firm conclusions about whether this is a cause-and-effect relationship, rather than a statistical blip, the result needs to be replicated in a much larger study."
Janet R. Daling, David R. Doody, Xiaofei Sun, Britton L. Trabert, Noel S. Weiss, Chu Chen, Mary L. Biggs, Jacqueline R. Starr, Sudhansu K. Dey, Stephen M. Schwartz (2009). Association of marijuana use and the incidence of testicular germ cell tumors Cancer DOI: 10.1002/cncr.24159