Daily Cannabis Use Surpasses Alcohol, Oral Cancer Risk Climbs

New Study Links Cannabis Use Disorder to Tripled Oral Cancer Likelihood

An unprecedented shift in substance use shows more Americans daily smoking cannabis than drinking alcohol. This trend, with approximately 17.7 million daily or near-daily cannabis users in 2022, amplifies concerns about the long-term health impacts of frequent consumption.

Cannabis Use Disorder and Oral Cancer Link Revealed

Researchers at the University of California San Diego (UCSD) analyzed data from over 45,000 patients. Their findings indicated that individuals diagnosed with cannabis use disorder (CUD) were 3.25 times more prone to developing oral cancer within a five-year period compared to those without the disorder. This heightened risk remained significant even after adjusting for factors like age, sex, body mass index, and tobacco smoking.

Raphael E. Cuomo, Ph.D., an associate professor at UC San Diego School of Medicine and a member of the Moores Cancer Center, led the study. He noted that these results align with existing toxicological data, which identifies many of the same cancer-causing chemicals in cannabis smoke as those found in tobacco smoke.

Understanding Problematic Cannabis Use

While cannabis legalization has increased accessibility, about 30% of regular users meet the clinical criteria for CUD, signaling problematic patterns. Unlike occasional use, CUD often involves daily smoking, deeper inhalations, and high-potency products that expose oral tissues to combustion byproducts.

The American Cancer Society estimates that approximately 59,660 Americans will be diagnosed with oral or throat cancers in 2025. While smoking remains a primary risk factor, the study suggests that cannabis use, alongside human papillomavirus (HPV) and heavy drinking, may contribute new layers to oral cancer risk.

Oral tumors often begin as painless spots, making early detection challenging. By connecting CUD with tumor incidence in electronic health records, the UC San Diego team provides clinicians with a crucial new indicator for vigilance.

Cannabis Elevates Cancer Risk Significantly

The study drew data from six academic medical centers between 2012 and 2019, with each participant followed for five years. A small subset, only 2.1% of participants, developed CUD, yet this group accounted for nearly a third of the oral cancer diagnoses observed.

Tobacco smokers in the study cohort already faced increased risks. However, those who both smoked cigarettes and had CUD were six times more likely to be diagnosed with oral cancer than smokers without CUD. The persistent cannabis risk signal within the smoking subgroup suggests mechanisms beyond simple smoke exposure may be at play, according to Cuomo’s team.

The research also observed that factors like female sex, older age, and higher body mass index appeared to slightly mitigate the risk, mirroring patterns seen with tobacco-related oral cancers. Nevertheless, these demographic influences did not eliminate the impact of CUD on cancer development.

Combustion Byproducts Harm Oral Tissues

Laboratory analyses reveal that marijuana smoke contains hundreds of polycyclic aromatic hydrocarbons (PAHs), benzene, and ammonia, often at concentrations equal to or higher than tobacco sidestream smoke. Several of these compounds are known to directly damage DNA in the epithelial cells lining the mouth.

A 2020 chemical analysis identified 2,575 distinct compounds in mainstream cannabis smoke, with 110 classified as known human toxicants. These particle-rich aerosols adhere to mucosal surfaces, prolonging contact time between carcinogens and susceptible cells.

Histological examinations of habitual marijuana smokers have revealed precancerous changes, such as dysplasia, in bronchial tissue, even in the absence of tobacco use. These cellular alterations are considered early indicators in the development of malignancies.

How Cannabis Affects Cancer Defenses

Tetrahydrocannabinol (THC), the primary psychoactive compound in cannabis, can interfere with immune suppression pathways that normally identify and eliminate rogue cells. Reduced immune surveillance could provide mutated oral cells a critical advantage in forming tumors.

While edible or vaporized cannabis products bypass the oral cavity, frequent users often employ multiple methods. Therefore, the risk patterns associated with noncombustible forms of cannabis remain unclear. Future research aims to differentiate risk factors by separating smoke exposure from total THC dosage.

An additional unknown is whether the increasing average potency of commercial cannabis accelerates carcinogen uptake or impacts immune functions. Public laboratories are beginning to simulate how today’s high-THC cannabis compares to the lower-potency products studied decades ago.

Daily Use Poses Significant Risk

Individuals with CUD often experience co-occurring mental health challenges, alcohol misuse, and reduced participation in preventive dental care. These combined factors can exacerbate cancer risk and delay diagnosis. Socioeconomic disparities may also play a role, as uninsured adults are less likely to receive routine oral examinations.

Community health initiatives that integrate substance use counseling with oral screenings could help address these disparities. For healthcare providers, the implication is clear: identifying CUD in patients warrants a thorough oral examination and potential referral to dental services, offering an opportunity for early detection.

Heavy Cannabis Consumption Impairs Oral Health

Cannabis is not merely a less potent alternative to tobacco; its smoke delivers a complex array of chemicals with measurable effects on human tissues. The UC San Diego study underscores that heavy, prolonged cannabis use carries consequences that are often overlooked in legalization discussions.

Policymakers considering retail expansion should ensure that cancer prevention messaging keeps pace with marketing efforts. Clear warnings, similar to those on tobacco products, could empower users to make more informed decisions about their health.

For individuals who use cannabis daily, reducing potential harm may involve switching to noncombustible products, moderating frequency, and maintaining regular dental check-ups. Researchers are continuing to explore the effects of dosage, delivery methods, and individual biology, but adopting cautious habits is a vital first step.

“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,” stated Cuomo. Awareness of this fundamental fact is crucial for making safer choices.

The findings of this study were published in Preventive Medicine Reports.