Key messages:
- Adults with cannabis dependence (i.e., cannabis use disorder) are 3.5 to 5 times more likely to develop head and neck cancer than those who do not use the substance.
- Prevalence of head and neck cancer among those with cannabis use disorder was independent of other factors (e.g., age, sex, and ethnicity).
- Oral health professionals play a role in informing clients about the potential risks of cannabis use in head and neck cancer development.
Introduction
Head and neck cancer (HNC) is the sixth most common cancer globally. HNC includes cancers of the oral cavity, pharynx, larynx, oropharynx (soft palate, side and back walls of the throat, tonsils, back one-third of the tongue) and salivary glands.
Historically, HNC was primarily associated with tobacco and excessive alcohol use, although recent data have demonstrated a rise in human papillomavirus (HPV)-related cancers. Research shows many HNCs are attributed to modifiable risk factors, highlighting the importance of detecting and preventing these underlying risk factors to decrease HNC prevalence.
Cannabis is the most commonly used substance worldwide and is primarily consumed through inhalation-based methods. Cannabis has been used for different medical conditions, such as nausea, anorexia, and cancer pain. Despite its purported benefits, cannabis use remains controversial due to its harmful association with the development of cannabis use disorder and other mental health conditions. To date, studies examining the association between cannabis and HNC risk are inconsistent.
Objective
This large multicentre cohort study from the University of Southern California assessed the association between cannabis use and HNC.
Design
The study used clinical records from a database that included 20 years of data from 64 healthcare organizations. The database was searched for medical records for US adults with and without a cannabis-related disorder and no prior history of HNC. Cannabis-related disorder is defined by the excessive use of cannabis with associated psychosocial symptoms (e.g., impaired social and/or occupational functioning). Propensity score matching was performed for demographic characteristics, alcohol-related disorders, and tobacco use. Relative risks were calculated to assess HNC risk, including types of HNC. This analysis was repeated among those younger than 60 years and 60 years or older.
Results
The cannabis-related disorder cohort included 116,076 individuals, and the non-cannabis-related disorder cohort included 3,985,286 individuals. The rate of new HNC diagnosis was higher in the cannabis-related disorder cohort. After matching, individuals with a cannabis-related disorder had a higher risk of any HNC than those without HNC (relative risk, 3.49). A site-specific analysis showed those with cannabis-related disorder had a higher risk of oral, oropharyngeal, and laryngeal cancer (relative risks, 2.51, 4.90, and 8.39, respectively). Results were consistent when stratifying by older and younger age groups.
Conclusions
This cohort study highlights 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 this association and understand the mechanism of this potential association.
