Cannabis users face a significantly higher oral cancer risk, similar to cigarette smokers

More people in the United States now smoke cannabis every day than drink alcohol, with about 17.7 million daily or near daily users recorded in the 2022 National Survey on Drug Use and Health.

That shift adds urgency to questions about what long term, high frequency use might be doing to the body.

Researchers from the University of California San Diego (UCSD) followed more than 45,000 patients. They found that people diagnosed with cannabis use disorder (CUD) were 3.25 times more likely to develop oral cancer within five years than those without the disorder.

The elevated risk held even after accounting for age, sex, body mass index, and tobacco smoking.

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

He points out that the findings dovetail with toxicology data showing cannabis smoke carries many of the same chemicals blamed for tobacco related malignancies.

Cannabis use linked to oral cancer

Legalization has widened access to cannabis, yet roughly three-in-ten regular users meet criteria for the disorder, a clinical diagnosis that signals problematic use.

Unlike casual consumption, CUD typically involves near daily smoking, deeper inhalation, and higher potency products that bathe oral tissues in combustion by products.

At the same time, the American Cancer Society estimates about 59,660 Americans will be told they have cancers of the mouth or throat in 2025.

Smoking remains a leading risk factor, but human papillomavirus (HPV), heavy drinking, and now cannabis may add new layers to that risk profile.

Oral tumors often begin as painless spots on the lip or tongue, making early detection tricky. By linking CUD and tumor incidence in electronic health records, the UC San Diego team offers clinicians a fresh flag for vigilance.

Cannabis raises cancer risk

The study drew data from six academic medical centers between 2012 and 2019, then tracked each participant for five years.

Only 2.1 percent developed CUD, yet that small group accounted for nearly a third of the oral cancer diagnoses observed.

Tobacco smokers in the cohort already faced extra danger, but those who both smoked cigarettes and had CUD were six times more likely to be diagnosed than smokers without CUD.

Because the cannabis signal persisted inside the smoking subgroup, Cuomo’s team suspects mechanisms beyond simple smoke exposure.

The researchers also noted that women, older age, and higher body mass index appeared to slightly temper risk, echoing patterns seen with tobacco related oral cancers. However, those demographic buffers did not erase the impact of CUD.

Smoke harms mouth tissue

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

A detailed chemical fingerprint published in 2020 cataloged 2,575 distinct compounds in mainstream cannabis smoke, 110 of which are known human toxicants.

Such particle rich aerosols stick to mucosal surfaces, extending contact time between carcinogens and target cells.

Histology from habitual marijuana smokers has revealed dysplasia and other precancerous changes in bronchial tissue even when tobacco is absent. Those cellular alterations mirror the earliest steps seen on the path to malignancy.

Cannabis affects cancer defense

Tetrahydrocannabinol (THC), the main psychoactive molecule in cannabis, can impair immune suppression pathways that normally patrol for rogue cells. Less immune surveillance could give mutated oral cells a head start toward tumor formation.

Edible or vaporized products bypass the oral cavity, yet frequent users often combine delivery methods, so risk patterns for noncombustible forms remain unclear.

Future studies that separate smoke exposure from total THC dose may untangle these variables.

Another unknown is whether the rising average potency of commercial cannabis accelerates carcinogen uptake or immune effects.

Public laboratories have only begun to simulate how today’s 25 percent THC flower compares with the 4 percent material studied decades ago.

Daily users face big risk

People with CUD commonly face co-occurring mental health challenges, alcohol misuse, and lower participation in preventive dental care. These overlapping factors could compound cancer risk and delay diagnosis.

Socioeconomic gaps may also play a role, because uninsured adults are less likely to receive routine oral examinations. Community clinics that integrate substance use counseling with oral screenings could bridge that divide.

For clinicians, the takeaway is straightforward. When a patient meets criteria for CUD, adding a quick inspection of the mouth and a referral to dentistry costs little but may spot trouble early.

Heavy cannabis harms oral health

Cannabis is not just a milder cousin of tobacco, its smoke delivers a complex chemical load with measurable impacts on human tissue.

The UC San Diego study reminds us that heavy, prolonged use carries consequences that legalization debates often overlook.

Policy makers weighing retail expansion should ensure that cancer prevention messaging keeps pace with marketing. Clear warnings, similar to those on cigarette packs, could help users make informed choices.

For now, anyone lighting up daily can lower potential harm by switching to noncombustible products, spacing out sessions, and keeping regular dental check ups.

Researchers will continue probing dose, delivery, and biology, but prudence starts with individual habits.

“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,” noted Cuomo.

Staying aware of that simple fact may be the first step toward safer choices.

The study is published in Preventive Medicine Reports.

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