medwireNews: A US study has found a significant association between excessive cannabis use and the development of head and neck cancer (HNC).
In the study cohort, the risk for HNC was 3.5 to 5.0 times greater for people with versus without cannabis-related disorders, report Niels Kokot (University of Southern California, Los Angeles, USA) and associates in JAMA Otolaryngology-Head & Neck Surgery.
They write: “The possibility of an association between cannabis use and HNC has substantial public health implications given that cannabis use is rising among young adults with trends toward legalization.”
Joseph Califano (University of California, San Diego, USA) and fellow authors of an accompanying comment agree that the implications of the findings “are sobering.”
They point out that “[o]ver the past decade, the US has seen an increased frequency of daily use and a doubling of current use rates, more than 5-fold increase in cannabinoid concentrations in recreational cannabis, expanded routes of administration including vaping and ingesting, and greater use of relatively pure forms of specific cannabinoids, including [tetrahydrocannabinol] and [cannabidiol].”
The commentators therefore say that if the identified association “is causative, the burden of [HNC] attributable to cannabis will continue to increase, and perhaps dramatically.”
Kokot et al queried TriNetX, a globally federated database of deidentified electronic medical records, to identify adults with (n=116,076) and without (n=3,985,286) cannabis-related disorders who had recorded outpatient hospital clinic visits and no prior history of HNC.
They found that the incidence of any HNC was higher in the cannabis-related disorders group than in the control group, at rates of 0.285% and 0.091%, respectively. This was also the case for all subtypes of HNC, including oral cancer (0.113 vs 0.049%), laryngeal cancer (0.093 vs 0.015%), oropharyngeal cancer (0.081 vs 0.013%), salivary gland cancer (0.023 vs 0.008%), nasopharyngeal cancer (0.022 vs 0.007%), and hypopharyngeal cancer (0.016 vs 0.003%).
After propensity score matching based on demographic characteristics, alcohol-related disorders, and tobacco use, there were 115,865 participants in each group and the risk for developing any HNC was significantly greater among those with versus without cannabis-related disorders, with a risk ratio (RR) of 3.49.
Cannabis-related disorders were also associated with a significantly increased risk for laryngeal cancer (RR=8.39), oropharyngeal cancer (RR=4.90), salivary gland cancer (RR=2.70), nasopharyngeal cancer (RR=2.60), and oral cancer (RR=2.51) but not hypopharyngeal cancer, which the authors speculate “may be due to underpowering of results.”
When the analysis were restricted to HNC cases that developed a year or more after the diagnosis of cannabis disorder, the association between excessive cannabis use and any HNC remained significant, with an RR of 4.40, with a further increase to 5.00 after limiting to HNC cases diagnosed after 5 years or longer.
The study authors conclude 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.”
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JAMA Otolaryngol Head Neck Surg 2024; doi:10.1001/jamaoto.2024.2419
JAMA Otolaryngol Head Neck Surg 2024; doi:10.1001/jamaoto.2024.2420