Study Links Marijuana Use to Increased Oral Cancer Risk

A recent study has revealed that individuals who regularly use marijuana may more than triple their chances of developing oral cancer.

Around half of adults in the U.S. report having tried marijuana at some point, with approximately 17.7 million experiencing symptoms of cannabis use disorder (CUD).

CUD is diagnosed when someone continues to use the drug despite negative effects on their life and relationships.

Researchers from the University of California, San Diego, tracked 45,000 individuals, some diagnosed with CUD, over five years. Findings indicated that daily smokers are about 3.25 times more likely to develop oral cancer compared to those without the disorder.

Dr. Raphael Cuomo, an anesthesiology professor and lead researcher, explained that cannabis smoke shares many carcinogenic compounds with tobacco smoke, known to harm the epithelial tissue in the mouth.

Interestingly, cannabis smoke contains a significant number of harmful chemicals—around 2,600—parallel to those found in tobacco smoke. This includes substances like polycyclic aromatic hydrocarbons (PAHs), benzene, and ammonia.

These chemicals can adhere to the mouth’s mucous membranes, allowing carcinogens to infiltrate oral tissues. Additionally, THC, the active component in marijuana, may inhibit vital immune responses that would typically detect and eliminate harmful cells.

Out of the participants in the study, 949 had CUD. Those who did not smoke or only smoked infrequently remained mostly abstinent throughout the study, with over 97% still classified as such upon follow-up.

During the research, 106 patients were diagnosed with oral cancer. The incidence rate was 0.23 percent among non-CUD individuals—similar to general population figures—while those with CUD saw a rate of 0.74 percent.

This type of cancer includes malignant growths in various parts of the mouth and throat. Statistically, about one in 59 men and one in 139 women are likely to develop oral cancer in their lifetime.

Oral cancers represent about three percent of the annual cancer diagnoses in the U.S., accounting for around 58,500 cases and 12,250 deaths each year.

The study’s outcomes may influence cancer screening protocols in both primary care and mental health environments since individuals with CUD often share various social and behavioral risk factors, including tobacco and alcohol use, along with a reduced inclination towards preventive healthcare.

Those with CUD who also smoke tobacco had a 6.24-fold increase in the risk of developing oral cancer. Age is another factor; with each additional year, cancer risk rises by approximately four times.

Similar to tobacco users, marijuana smokers experience damage to lung and throat cells, possibly leading to abnormal cell growth. It’s worth noting that these damaging effects can also be present in non-tobacco users, suggesting that marijuana smoke can be independently harmful.

Dr. Cuomo remarked that these findings contribute to a growing body of evidence indicating chronic cannabis use could elevate cancer risk in tissues exposed to combustion products.

The results were published in *Preventive Medicine Reports*. In the U.S., marijuana is fully legal for both recreational and medicinal purposes in 29 states, while it remains completely illegal in four states.

A significant majority, around 88 percent, support marijuana legalization, according to the Pew Research Center, though there are concerns from public health experts regarding long-term effects that remain somewhat elusive to scientists.

In June, another study by UC researchers investigated heart health related to cannabis use across 200 million individuals, finding notably higher risks for acute coronary syndrome, strokes, and cardiovascular disease among users.

Additionally, recent FDA trial findings suggested that certain CBD users experienced dangerous liver enzyme spikes, raising the specter of potential chronic liver damage, although all participants’ liver tests normalized after discontinuing CBD usage.

Regular consumption of potent cannabis during adolescence may also alter brain structures, particularly affecting the prefrontal cortex, which regulates decision-making and impulse control—critical during a period when psychotic disorders can emerge.

THC might even trigger schizophrenia or psychotic episodes in individuals genetically predisposed to these conditions. A 2022 review indicated that users of high-potency cannabis were significantly more likely to develop addictive behaviors and experience psychotic breaks compared to those using lower-potency strains.

In Ontario, Canada, emergency visits linked to schizophrenia among marijuana users have tripled since legalization, with the rate of schizophrenia among those with CUD rising from four percent to over ten percent from 2006 to 2022, in contrast to just 0.6 percent among non-users.