Oral cancer risk triples among individuals with cannabis use disorder

A recent study by researchers at the University of California San Diego School of Medicine has found that individuals with cannabis use disorder (CUD) are more than three times more likely to develop oral cancer within five years compared to those without CUD. The study highlights the potential long-term health risks associated with problematic cannabis use.

In 2022, 17.7 million people reported daily or near-daily cannabis use. Though CUD requires a formal diagnosis and not all cannabis users develop the disorder, recent research suggests that as many as 3 in 10 cannabis users will develop CUD.

As cannabis becomes more widely available and socially accepted, it is essential to understand its potential health risks. While many consider cannabis to be safer than other drugs, such as tobacco and alcohol, there are still many unknowns about the health impacts of cannabis, particularly how the drug influences cancer risk. The new study sought to determine the relationship between CUD and oral cancer, for which tobacco smoking is known to be a significant risk factor.

Cannabis smoke contains many of the same carcinogenic compounds found in tobacco smoke, which have known damaging effects on the epithelial tissue that lines the mouth. These findings add to a growing body of evidence suggesting that chronic or problematic cannabis use may contribute to cancer risk in tissues exposed to combustion products."

Raphael Cuomo, Ph.D. associate professor in the Department of Anesthesiology at UC San Diego School of Medicine and member of UC San Diego Moores Cancer Center

By analyzing the electronic health records from over 45,000 patients, of whom 949 developed CUD, Cuomo found:

• After adjusting for age, sex, body mass index and smoking status, people had a 325 percent times higher likelihood of contracting oral cancer within five years compared to those without CUD.
• Tobacco smokers with CUD were 624 percent more likely to contract oral cancer within five years compared to tobacco smokers without CUD.

Because the association between CUD and oral cancer remained even after controlling for smoking status, and because CUD was associated with greater oral cancer risk even when the analysis was restricted to smokers, the researchers hypothesize that there may be other factors underlying this risk in addition to smoke inhalation. For example, THC, the active compound in cannabis is known to have immune-suppressing effects, which may contribute to increased cancer risk.

While more research is needed to fully explain the association between cannabis and oral cancer, the study's results have immediate implications for cancer screening practices and public health messaging. In particular, the findings emphasize the need for further research on the long-term effects of cannabis use and the importance of integrating oral health awareness into substance use disorder treatment and counseling.