Cannabis Overuse Linked to Increased Risk for Head and Neck Cancer

TOPLINE:

Cannabis-related disorders are associated with a more than a threefold increased risk for head and neck cancer. The study analyzed data from over four million patients, highlighting the potential carcinogenic effects of the substance.

METHODOLOGY:

• Researchers analyzed data from a globally federated health research network TriNetX, which included over 90 million men and women from 64 health care organizations in the United States.
• More than 4.1 million patients were included in the analysis, including 116,076 individuals diagnosed with cannabis-related disorder and 3.9 million without the disorder. Cannabis-related disorders involve the excessive use of cannabis with associated psychosocial symptoms, such as impaired social and/or occupational functioning.
• Patients with cannabis-related disorder were matched with those without the disorder based on demographic characteristics, alcohol-related disorders, and tobacco use.
• The primary outcome was the diagnosis of head and neck cancer, including subsites such as oral, oropharyngeal, nasopharyngeal, laryngeal, hypopharyngeal, and salivary gland malignancies.
• Propensity score matching and Poisson regression analysis were used to compare the incidence of head and neck cancers between the groups.

TAKEAWAY:

• According to the researchers, patients with a cannabis-related disorder had a higher risk for any head and neck cancer (relative risk [RR], 3.49; 95% CI, 2.78-4.39) than those without the disorder.
• The risk for specific cancers was also higher in the group with cannabis-related disorders, including oral (RR, 2.51; 95% CI, 1.81-3.47) and oropharyngeal malignancies (RR, 4.90; 95% CI, 2.99-8.02).
• The RR for laryngeal cancer was significantly higher in the patients with a cannabis-related disorder (RR, 8.39; 95% CI, 4.72-14.90).
• The findings suggest that cannabis use disorder is associated with an increased risk for head and neck cancers, highlighting the need for further research to understand the mechanisms involved.

IN PRACTICE:

“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. When limited to cases of [such cancers] occurring greater than 1 year after cannabis use disorder diagnosis, many of the associations increased, demonstrating additional strength in the association,” the authors of the study wrote.

“The association of cannabis and head and neck cancer in this study spanned 2 decades during a rapid growth in use. If this association is causative, the burden of [head and neck cancers] attributable to cannabis will continue to increase, and perhaps dramatically,” said the authors of an editorial accompanying the journal article. “Given that cannabis is now a $20 billion industry in the US alone with expanding availability, use, and popularity, this may be “déjà vu, all over again” without appropriate research to understand the potential carcinogenic and salutatory effects of cannabis. Or, in the words of Yogi Berra, “If you don’t know where you are going, you might wind up someplace else.”