August 12, 2024 from Medscape
A recent study has revealed a concerning connection between cannabis use disorder and a significantly increased risk of head and neck cancers. The research, published in JAMA Otolaryngology-Head & Neck Surgery, analyzed data from over four million patients, providing robust evidence of the potential carcinogenic effects of cannabis.
Study Overview
Researchers from the Keck School of Medicine of the University of Southern California conducted the study using data from the TriNetX global health research network. This extensive database included information from over 90 million individuals across 64 healthcare organizations in the United States. The study focused on 4.1 million patients, of whom 116,076 were diagnosed with cannabis-related disorder, characterized by excessive cannabis use leading to impaired social and occupational functioning.
The primary aim was to assess the incidence of head and neck cancers—including oral, oropharyngeal, nasopharyngeal, laryngeal, hypopharyngeal, and salivary gland malignancies—among those with and without cannabis use disorder. The researchers employed propensity score matching and Poisson regression analysis to compare cancer risk between the two groups.
Key Findings
Patients with cannabis use disorder had a more than threefold increased risk of developing any form of head and neck cancer (Relative Risk [RR], 3.49; 95% CI, 2.78-4.39). The risk was even higher for specific types of cancer, such as laryngeal cancer, which showed an eightfold increase in risk (RR, 8.39; 95% CI, 4.72-14.90).
“In this cohort study, cannabis disorder diagnosis was independently associated with greater risk of subsequent development of any head or neck cancer as well as cancers in various subsites of the head and neck among US adults,” the study authors noted. They also observed that the association became even stronger when considering cancers diagnosed more than a year after the initial cannabis use disorder diagnosis.
Implications for Practice
These findings raise important concerns about the long-term effects of cannabis use, particularly as its use continues to grow in popularity. As the researchers highlighted, “If this association is causative, the burden of head and neck cancers attributable to cannabis will continue to increase, and perhaps dramatically.”
Given the expanding legal and social acceptance of cannabis, further research is needed to understand the underlying mechanisms that link cannabis use disorder with increased cancer risk. Additionally, healthcare providers should be aware of these risks when discussing cannabis use with their patients, especially those who may be at higher risk for head and neck cancers.
Study Limitations
While the study provides compelling evidence, it is not without limitations. The researchers acknowledged that the study’s reliance on medical record codes and the lack of detailed information on cannabis dosage, frequency, and duration may have introduced biases. Moreover, the potential underreporting of cannabis use could have affected the relative risks identified in the study.
Despite these limitations, the study offers critical insights that could inform future research and clinical practice. As the editorial accompanying the study pointed out, the growing cannabis industry and its widespread use could lead to a significant public health burden if the association between cannabis use disorder and cancer is indeed causative.
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