Scientists Discover New Link Between Marijuana Smoking And Testicular Cancer Risk

JULIA NAFTULIN, 

There's new evidence that a daily marijuana-smoking habit could increase your risk of testicular cancer.

A study published Wednesday in JAMA Network Open found that men who smoked one marijuana cigarette, or joint, daily for 10 years or more had an estimated 36 percent increased risk of developing testicular cancer compared with men who had never smoked the substance.

To come to their conclusion, researchers analysed 25 studies that looked at the link between marijuana use and testicular cancer, lung cancer, oral cancer, and head and neck cancer.

Though the researchers found no association between regular marijuana use and lung, neck, or oral cancer, they did find that regular weed smoking over many years could heighten a man's risk of testicular cancer.

Smoking marijuana releases cancer-causing substances

Like smoking cigarettes, smoking marijuana releases carcinogens, or substances that can increase a person's risk of developing cancer.

That's because cannabis, the plant marijuana is derived from, is like any other plant in that it burns and releases smoke when you light it, according to Dr. Jeffrey Chen, the director of the UCLA Cannabis Research Initiative.

"When you combust any plant, you're creating significantly more carcinogens," Chen previously told Insider.

The study's researchers were unable to determine why their meta-analysis showed a link between smoking pot and testicular cancer but none of the other three cancers they analysed.

They did, however, note that the varying populations of each study they analysed could have contributed to their findings. For example, the meta-analysis included only studies written in English, which could have left out large swaths of the population.

Additionally, since the studies were published between 1973 and 2018, some of the older studies may not reflect the current population's marijuana-consumption habits. And, of course, the study can't prove a cause-and-effect relationship.

Nonetheless, the researchers said their study offers insights into how long-term marijuana smoking could affect men and raises red flags about new, understudied consumption methods like vaping.

And as marijuana is legalised in more places, more people may be picking up marijuana-smoking habits, so it's important to understand the substance's health risks, the researchers wrote.

Testicular cancer is the most common cancer in young men

According to the National Organisation for Rare Disorders, though testicular cancer accounts for only 1 percent of cancers in men, it's the most commonly diagnosed cancer in men between 15 and 35. Every year in the US, an estimated 8,850 men are diagnosed with the disease.

According to NORD, the most common symptom of testicular cancer is a firm but painless bump – a cancerous tumour – on the testicle. If one testicle swells, that can also be a sign of cancer.

Other symptoms include aching in the stomach or scrotum areas, nausea, weight loss, vomiting, and difficulty breathing.

Testicular cancer is one of the most treatable forms of cancer, according to NORD. It's usually curable with surgery, and sometimes also requires radiation or chemotherapy.