Marijuana linked to testicular cancer

FREQUENT use of marijuana may be linked to testicular cancer, a report has found.

The study showed marijuana use was a significant risk factor for the disease.

The US research also discovered current marijuana use was linked to a 70% increased risk for the disease.

It was particularly elevated — about twice that of those who never smoked marijuana — for those who used the drug at least once a week and/or who had long-term exposure to the substance beginning in adolescence.

The results also suggested the association with marijuana use might be limited to nonseminoma, a fast-growing testicular malignancy which tends to strike early, aged between 20 and 35, and accounts for about 40% of all cases.

Researchers were prompted to check an association between the drug and the disease when they realised that since the 1950s the incidence of the two main cellular subtypes of testicular cancer, nonseminoma and seminoma — the more common, slower growing kind which strikes men in their 30s and 40s — had increased by 3% to 6% in the US, Canada, Europe, Australia and New Zealand, and marijuana use had risen accordingly.

Author Stephen Schwartz, an epidemiologist at the Seattle’s Fred Hutchinson Cancer Research Center, said: “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.”

Established risk factors include a family history of the disease, undescended testes and abnormal testicular development.

The male reproductive system naturally produces a cannabinoid-like chemical that is thought to have a protective effect against cancer. The authors speculate that marijuana use may disrupt this anti-tumour effect, which could be an explanation for the possible link.

The researchers interviewed 369 men in the Seattle-Puget Sound area, aged 18 to 44, who had been diagnosed with testicular cancer, about their history of marijuana use.

For comparison purposes, they also assessed marijuana use among 979 randomly selected people without the disease.

People taking part in the study were also asked about other habits that might be correlated with marijuana use, including smoking and alcohol consumption.

Even after statistically controlling for these and other factors, such as family history of testicular cancer and a history of undescended testes, marijuana use emerged as a significant, independent risk factor.

The researchers emphasised their results were not definitive, but should lead to more research questions.