Researching marijuana has historically been extremely difficult because the government implemented tight restrictions on the drug that severely limited scientists’ ability to study it. But now, as legal barriers surrounding marijuana continue to fall, we’re seeing an influx of new research.
Today, it’s not known exactly how and in what ways marijuana affects the body, but we’re starting to learn more about it. A worrying study published in 2019 in the Journal of the American Medical Association (JAMA), found that marijuana may increase testicular cancer risk in men.
A team of American researchers analyzed data from 25 different studies involving regular cannabis use in adults and subsequent cancer risk. They defined “regular cannabis use” as smoking at least one joint per day. Then, they compared cancer risks between smokers and non-smokers. The researchers found no significant evidence linking marijuana to any type of cancer–other than testicular cancer. However, it’s important to note that the researchers admitted that the evidence they did find was “low-strength,” meaning they didn’t have anything concrete. The researchers did not study the effects of using any other type of marijuana, such as edibles.
“Low-strength evidence suggests that smoking marijuana is associated with developing [testicular cancer]; its association with other cancers and the consequences of higher levels of use are unclear. Long-term studies in marijuana-only smokers would improve understanding of marijuana’s association with lung, oral, and other cancers,” the researchers wrote.
Although the results weren’t exactly clear, it’s still something to consider before choosing to use cannabis. It’s likely, though, that many of the negative effects attributed to the drug come from smoking it, as combustion of any substance releases many carcinogens into the body.
Earlier studies on the topic also found a link between marijuana and testicular cancer. A 2012 study from the University of Southern California found a “potential” association between cannabis and testicular cancer. But the study only recruited around 450 men overall, a relatively small sample size. In 2018, though, a much larger study was done. 49,343 Swedish men aged 18 to 21 were followed over the course of 45 years, from 1970 to 2011. Their cannabis use was self-reported. The study concluded that those who used cannabis at some point during their lifetime had no increased risk of testicular cancer, but those who smoked cannabis more than 50 times in their lifetime (defined as “heavy” cannabis use) were 2.5 times more likely to develop testicular cancer.
Based on the above studies, it’s possible that marijuana can increase one’s risk of testicular cancer, if used regularly. Although the research isn’t fully clear, men may want to limit their cannabis use, or stop it entirely, if they’re concerned.
Written by Natan Rosenfeld
- Association Between Marijuana Use and Risk of Cancer
- Population‐based case‐control study of recreational drug use and testis cancer risk confirms an association between marijuana use and nonseminoma risk
- Cannabis use and incidence of testicular cancer: a 42-year follow-up of Swedish men between 1970 and 2011