In a cohort study of patients with and without 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 related to the development of HNC and to further analyze dose-response relationships to find evidence of the association between cannabis and HNC.
“(HNC) is the sixth most common cancer worldwide, with more than 870,000 new cases and 440,000 deaths in 2020. In the United States alone, HNC accounts for nearly 3% of all cancers and more than 1.5% of all cancer deaths. HNC encompasses a diverse group of cancers of the mucosal epithelial linings of the upper aerodigestive tract, including the oral cavity, pharynx and larynx, and adjacent salivary glands. In the past, HNC has been associated primarily with tobacco-based carcinogens and/or excessive alcohol consumption,” said the authors of a study published in JAMA Otorhinolaryngology.1
Key findings
- The researchers’ goal was to better understand the connection between cannabis use and the development of head and neck cancer (HNC).
- The data showed that the cohort of patients with a cannabis-related disorder had a significantly higher risk of developing some type of HNC than participants who did not suffer from a cannabis-related disorder.
Now, coming to the trends in cannabis consumption, cannabis is currently the most commonly consumed illegal substance in the US and worldwide, and the numbers continue to rise. The most popular method of consuming cannabis is by inhaling. Researchers also mentioned that the cannabinoid derivatives in cannabis “induce unique gene expression profiles, inflammatory pathways, and oxidative stressors.” In the past, cannabis has also been observed as a treatment for nausea, anorexia, and cancer, among other diseases.1
“Ultimately, it remains unclear whether the association between cannabis use and HNC is similar to that of tobacco use. We hypothesized that there is an association between cannabis use and HNC due to the inflammatory effects of smoke on the upper airways and the potential carcinogenic mechanisms of cannabis,” the authors continued.
As more and more people consume cannabis, parallel research is being conducted to better understand the long-term health effects of the substance. Image credit: Elroi / stock.adobe.com
Using data from hospital outpatients from April 2004 to April 2024, the researchers assembled two cohorts: 116,076 patients in the cannabis-related disorders cohort (mean age 46.4; 52.9% male) and 3,985,286 patients in the non-cannabis-related disorders group (mean age 60.8; 54.5% male). After propensity score matching, the researchers further divided the study population into two groups of 115,865 people – one group with patients with cannabis-related disorders and the other group without.
HNC was significantly more common in the cannabis-related disease group, with patients in this cohort having higher rates for all 6 types of HNC observed in this study. The researchers also measured both groups’ risk of developing HNC after what they defined as the “index event,” which is a study participant’s first outpatient hospital visit.
READ MORE: DEA wants to classify marijuana as a less dangerous drug
“After restricting to cases of HNC occurring 1 year or more after the index event, the relative risk of developing HNC after a cannabis-related disease increased for each HNC, oral cavity cancer, and oropharyngeal cancer. After 1 year or more, the relative risk decreased but remained significant for laryngeal cancer, while the association with outcomes of nasopharyngeal carcinoma and salivary gland cancer became less significant. After restricting to cases of HNC occurring 5 years or more after the index event, the relative risk of developing cancer after a diagnosis of cannabis-related disease increased again for each HNC,” they wrote.1
Finally, they assessed HNC risks by observing only younger or older adults within the population. Both older and younger adults in the cannabis group had higher relative risks for HNC, laryngeal cancer, oral cavity cancer, and oropharyngeal cancer.
Despite the variability in the change in relative risks over time, patients in the cannabis-related disorder group had a significantly higher risk of developing any type of HNC. A strength of this study is its observation period of over 5 years. These results support the association between cannabis use and the development of HNC, with the data generally consistent throughout.
“Today, marijuana use is increasing among all age groups, both sexes, and among pregnant women. The highest rates of use are among people between the ages of 18 and 25. Marijuana and THC remain illegal at the federal level, although many states have legalized their use. In states where marijuana is legal, it is a rapidly growing industry, sold to people over 21 in retail stores, wineries, breweries, cafes, dispensaries, online, and home-grown,” the Substance Abuse and Mental Health Services Administration wrote.2
In fact, cannabis use is on the rise around the world. And as more people – especially younger populations – begin using cannabis, research is being conducted to help health professionals better understand the long-term health effects of the substance.
“This cohort study suggests that there is an association between excessive cannabis use and HNC, particularly oral, oropharyngeal and laryngeal cancer. These findings were consistent regardless of the age group studied. Further research is needed to confirm the existence of this association and to understand the mechanism of this potential association,” the authors concluded.1
READ MORE: Slideshow: Exploring Cannabis Use in the Oncology Landscape
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