Tobacco smokers with a cannabis addiction are 624% more likely to develop oral cancer within five years, a new study reveals.
Previous studies have shown that cigarette smokers are five to 10 times more likely to develop oral cancer compared to non-smokers.
Now, research from UC San Diego suggests that marijuana use may pose a similar or even higher risk. The study found that individuals with cannabis use disorder are 3.25 times more likely to be diagnosed with oral cancer within five years than those without the condition.
“Cannabis smoke contains many of the same carcinogenic compounds found in tobacco smoke, which can damage the epithelial tissue lining the mouth,” said Raphael Cuomo, a professor at the UC San Diego School of Medicine.
The study analyzed data from more than 45,000 oral cancer patients, including 949 diagnosed with cannabis use disorder. Researchers considered factors like age, gender, BMI, and smoking habits. They concluded that tobacco smokers who also have a cannabis addiction are over six times more likely to develop oral cancer than cigarette smokers who don’t use marijuana.
Oral cancer includes cancers of the lips, tongue, gums, inner cheeks, and mouth lining. Known risk factors include tobacco use, chronic alcohol consumption, and HPV infection.
The American Cancer Society estimates nearly 60,000 new cases of oral cavity or oropharyngeal cancer in the U.S. this year, with about 12,800 deaths expected.
The findings suggest that the increased cancer risk is likely due to inhaling smoke, as cannabis edibles and THC-infused beverages don’t show the same threat. Cuomo recommends regular self-checks and dental visits for all cannabis users, given the evolving nature of research.
He also advises seeing a dentist or an ENT specialist if any sore, ulcer, or red or white patch in the mouth persists for more than two weeks, especially if accompanied by a lump, bleeding, numbness, or pain when swallowing. Early detection is key, as oral cancers caught in the initial stage are often curable.
This UC San Diego study adds to mounting evidence, including a 2024 University of Southern California study linking daily marijuana use to a three- to five-fold increase in head and neck cancers — a group that includes oral cancer.
The researchers urge greater awareness of oral health risks in cannabis users and recommend integrating oral cancer education into substance abuse treatment programs.
