Cannabis Use and Head and Neck Cancer

Importance Cannabis is the most commonly used illicit substance worldwide. Whether cannabis use is associated with head and neck cancer (HNC) is unclear. Objective To assess the clinical association between cannabis use and HNC. Design, Setting, and Participants This large multicenter cohort study used clinical records from a database that included 20 years of data (through April 2024) from 64 health care organizations. A database was searched for medical records for US adults with and without cannabis-related disorder who had recorded outpatient hospital clinic visits and no prior history of HNC. Propensity score matching was performed for demographic characteristics, alcohol-related disorders, and tobacco use. Subsequently, relative risks (RRs) were calculated to explore risk of HNC, including HNC subsites. This analysis was repeated among those younger than 60 years and 60 years or older. Exposure Cannabis-related disorder. Main Outcomes and Measures Diagnosis of HNC and any HNC subsite. Results The cannabis-related disorder cohort included 116 076 individuals (51 646 women [44.5%]) with a mean (SD) age of 46.4 (16.8) years. The non-cannabis-related disorder cohort included 3 985 286 individuals (2 173 684 women [54.5%]) with a mean (SD) age of 60.8 (20.6) years. The rate of new HNC diagnosis in all sites was higher in the cannabis-related disorder cohort. After matching (n = 115 865 per group), patients with cannabis-related disorder had a higher risk of any HNC (RR, 3.49; 95% CI, 2.78-4.39) than those without HNC. A site-specific analysis yielded 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) cancer. Results were consistent when stratifying by older and younger age group. Conclusions and Relevance This cohort study highlights an association between cannabis-related disorder and the development of HNC in adult patients. Given the limitations of the database, 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.