A cohort study was conducted to address the association between patients with cannabis-related disorders and their risk of developing head and neck cancer.
In a matched cohort study analyzing patients both with and without a cannabis-related disorder, researchers found that cannabis users were more likely to develop head and neck cancer (HNC) in adulthood. After analyzing the data, they suggest further research to better understand how cannabis use is linked to the development of HNC and further analyze dose responses for evidence regarding the cannabis and HNC association.
“[HNC] is the sixth most frequent cancer type worldwide, with more than 870,000 new cases and 440,000 deaths in 2020. In the US alone, HNC accounts for nearly 3% of all cancers and more than 1.5% of all cancer deaths. HNCs include a diverse group of cancers from the mucosal epithelial linings of the upper aerodigestive tract, including the oral cavity, pharynx, and larynx, and adjacent salivary glands. Historically, HNC has been primarily associated with tobacco-derived carcinogens and/or excessive alcohol consumption,” according to authors of a study published in JAMA Otolaryngology Head & Neck Surgery.1
Moving over to trends within cannabis use, it is currently the most used illicit substance in both the US and in the world, and those numbers are continuing to increase. The most popular method of consuming cannabis is through inhalation. Researchers were also sure to mention that the cannabinoid derivatives in cannabis “induce unique gene expression profiles, inflammatory pathways, and oxidative stressors.” It’s also been observed in the past as a treatment for nausea, anorexia, and cancer, among other illnesses.1
“Ultimately, it remains unclear if the association between cannabis use and HNC is similar to that of tobacco use. We hypothesized that there would be an association between cannabis use and HNC due to the inflammatory effects of smoke on the upper airway and potential carcinogenic mechanisms of cannabis,” continued the authors.
Using outpatient hospital data from April 2004 to April 2024, researchers assembled 2 cohorts: 116,076 patients in the cannabis-related disorder cohort (mean age, 46.4; 52.9% men) and 3,985,286 patients in the non-cannabis-related disorder group (mean age, 60.8; 54.5% men). After propensity score matching, researchers further separated the study population into 2 groups of 115,865 individuals—one group containing patients with cannabis-related disorders and the other group not.
HNC was significantly more prevalent in the cannabis-related disorder group, with this cohort’s patients exhibiting higher rates for all 6 types of HNC observed in this study. Researchers also measured both groups’ risk of developing HNC after what they defined as the “index event,” which was considered the first recorded outpatient hospital visit for a study participant.
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“After limiting to cases of HNC developed 1 year or longer after the index event, the relative risk for developing HNC after cannabis disorder increased for any HNC, oral cancer, and oropharyngeal cancer. At 1 year or longer, the relative risk decreased but remained significant for laryngeal cancer, while the association lost significance with the outcomes of nasopharyngeal cancer and salivary gland cancer. After limiting to cases of HNC developed 5 years or longer after the index event, the relative risk for developing cancers after cannabis disorder diagnosis increased again for any HNC,” they wrote.1
Finally, they evaluated HNC risks when observing only younger or older adults within the population. Both older and younger adults in the cannabis group demonstrated higher relative risks for any HNC, laryngeal cancer, oral cancer, and oropharyngeal cancer.
Despite the variations in change of relative risks over time, patients in the cannabis-related disorder group showed a significantly higher risk of developing any type of HNC. With a strength of this study being its follow-up period of over 5 years, these results strengthen the association between cannabis use and the development of HNC, with generally consistent data across the board.
“Today, marijuana use is on the rise among all adult age groups, both sexes, and pregnant women. People ages 18-25 have the highest rate of use. Marijuana and THC remain illegal at the federal level, even though many states have legalized its use. In states where legal, marijuana is a fast-growing industry with sales to individuals over 21 in retail stores, wineries, breweries, coffee shops, dispensaries, online, as well as grown at home,” wrote the Substance Abuse and Mental Health Services Administration.2
Indeed, cannabis use is on the rise globally. And as more and more individuals—especially younger populations—begin using cannabis, simultaneous research will be conducted for health care experts to better understand the substance’s long-term health outcomes.
“This cohort study suggests that there is an association between excessive cannabis use and HNC, particularly oral, oropharyngeal, and laryngeal cancers. These findings were consistent regardless of the age group studied. Further research is necessary to confirm the existence of this association and understand the mechanism of this potential association,” concluded the authors.1
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