Daily Cannabis Use Linked to Increased Risk of Head and Neck Cancers

Daily cannabis use over a period of years may be linked to a significantly increased risk of head and neck cancers (HNCs), according to a recent study published in JAMA Otolaryngology Head & Neck Surgery. 

In this large, multicenter, cohort study, researchers analyzed clinical records from a database comprising 20 years of data to assess 116,076 individuals from 64 health care organizations. Specifically, the database search focused on medical records for US adults with and without cannabis-related disorder who had recorded outpatient hospital clinic visits and no prior history of HNC.

The investigators used relative risks (RRs) to discern the risk of HNCs, including HNC subsites. The primary end point of interest was the diagnosis of HNC and any HNC subsite.

Findings May Indicate a Rise in HNC Cases

The study showed that the rate of new HNC diagnoses in all sites was higher in the cannabis-related disorder cohort compared with the non–cannabis-related disorder cohort comprising 3,985,286 individuals. Subsequent to matching (n=115, 865 per group), investigators observed that patients with cannabis-related disorder had a higher risk of any HNC (RR, 3.49; 95% CI, 2.78-4.39) than those without. Also, a site-specific analysis showed that those with cannabis-related disorder had a higher risk of oral (RR, 2.51; 95% CI, 1.81-3.47), oropharyngeal (RR, 4.90; 95% CI, 2.99-8.02), and laryngeal (RR, 8.39; 95% CI, 4.72-14.90) cancers, and these results were consistent when stratified by age.

While the study highlighted a link, the researchers noted that “future research should examine the mechanism of this association and analyze dose response with strong controls to further support evidence of cannabis use as a risk factor for HNCs.”

In a CNN article about the study, Dr. Niels Kokot, a professor of clinical otolaryngology-head and neck surgery at the Keck School of Medicine, said, “Especially as [marijuana] becomes more widely legalized and socially accepted, we may see a corresponding rise in HNC cases if the association is confirmed. This underscores the importance to inform people about the potential risks and conduct further research to understand the long-term impacts of cannabis use on cancer development.”