‘Sobering’ data show excessive cannabis use increases risk for head and neck cancer
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Key takeaways:
- People with cannabis-related disorder exhibited increased risk for head and neck cancer.
- Subtypes with the greatest risk increase included laryngeal and oropharyngeal cancers.
Individuals with cannabis-related disorder exhibited increased risk for head and neck cancer, results of a retrospective cohort study showed.
The extent of the association varied by subtype but appeared particularly strong for laryngeal cancer and oropharyngeal cancer.
“The results aligned with our expectations, although the consistency of the association over different time frames was more nuanced and challenging to predict, reinforcing our belief in its validity,” Niels C. Kokot, MD, head and neck surgeon at Keck Medicine of USC, told Healio. “It’s crucial to emphasize the importance of making informed choices about cannabis use considering these findings.”
Background and methods
Head and neck cancers account for 3% of cancer incidence and 1.5% of cancer mortality in the U.S., according to study background.
Tobacco has long been associated with head and neck cancer development, and cannabis has similar carcinogens.
More than 42% of young adults reported using cannabis within the previous year, and usage had increased over the past 5 and 10 years, though down slightly from peaks in 2022, according to University of Michigan annual report on substance use among people aged 19 to 65 years.
Individuals with head and neck cancer have used cannabis to help alleviate pain and improve well-being.
Kokot and colleagues investigated whether cannabis use had any association with cancer occurrence.
They used the U.S. Collaborative network and TriNetX to evaluate two cohorts of people who had no history of head and neck cancer and had an outpatient hospital visit between April 19, 2004, and April 19, 2024.
The first group included 116,076 individuals (mean age, 46.4 years; 52.9% men; 60% white) who had a diagnosis of cannabis-related disorder.
Researchers defined cannabis-related disorders as excessive cannabis use with associated psychosocial symptoms, including impaired occupational or social functioning.
The second cohort included 3,985,286 people (mean age, 60.8 years; 54.5% women; 74.6% white) who did not have a cannabis-related disorder.
The analysis included 115,865 individuals from each cohort matched for age, self-reported race and ethnicity, tobacco use and alcohol-related disorders.
Results and next steps
Results showed significantly higher head and neck cancer risk in the cannabis-disorder cohort (RR = 3.49; 95% CI, 2.78-4.39).
People in this group had substantially higher risks for several subtypes, including laryngeal cancer (RR = 8.39; 95% CI, 4.72-14.9), oropharyngeal cancer (RR = 4.9; 95% CI, 2.99-8.02), salivary gland cancer (RR = 2.7; 95% CI, 1.31-5.58), nasopharyngeal cancer (RR = 2.6; 95% CI, 1.25-5.39) and oral cancer (RR = 2.51; 95% CI, 1.81-3.47).
When researchers limited analyses to diagnoses that occurred at least 1 year after index event, the elevated risk among people with cannabis-related disorder persisted for any head and neck cancer (RR = 4.4; 95% CI, 3.21-6.01), oropharyngeal cancer (RR = 6.7; 95% CI, 3.45-13.03) and oral cancer (RR = 3.11; 95% CI, 2.02-4.08).
Analyses limited to diagnoses that occurred at least 5 years after index event showed a significantly increased risk in the cannabis-related disorder group for any head and neck cancer (RR = 5; 95% CI, 2.62-9.56) but not for any specific subtypes,
“The clearest potential association between [head and neck cancer and cannabis use] lies in the inflammatory pathways that are triggered by cannabis smoke, as smoking is the most common method of cannabis consumption,” Kokot and colleagues wrote. “Compared with smoking tobacco, smoking cannabis may be even more proinflammatory.
“Cannabis smoking is typically unfiltered and consumed through deeper breaths than tobacco,” they added. “Additionally, cannabis burns at a higher temperature than tobacco, increasing the risk [for] inflammatory injury. On a cellular level, cannabis smoke increases the expression of epidermal growth factor receptor, which has been found to be overexpressed in most cases of squamous cell carcinoma in the head and neck, as well as in laryngeal cancer specimens from people who smoke cannabis.”
Researchers acknowledged study limitations, including lack of information about “cohort composition,” including population characteristics, health care organizations included and payer status. They also cited lack of information about frequency and dosage of cannabis use.
“The next steps involve designing studies to determine the amount and type of cannabis use and how these factors impact the risk for head and neck cancer,” Kokot told Healio. “This will help us better understand the specifics of this association.”
The study findings are “sobering,” Joseph A. Califano III, MD, director of UC San Diego Health’s Hanna and Mark Gleiberman Head and Neck Cancer Center, and colleagues wrote in an accompanying editorial.
“The association of cannabis and head and neck cancer in this study spanned 2 decades during a rapid growth in use,” they wrote. “If this association is causative, the burden of head and neck squamous cell carcinoma attributable to cannabis will continue to increase, and perhaps dramatically. Given that cannabis is now a $20 billion industry in the U.S. 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.”
For more information:
Niels C. Kokot, MD, can be reached at laura.nuno@med.usc.edu.
References:
- Califano J, et al. JAMA Otolaryngol Head Neck Surg. 2024;doi:10.1001/jamaoto.2024.2420.
- Gallagher TJ, et al. JAMA Otolaryngol Head Neck Surg. 2024;doi:10.1001/jamaoto.2024.2419.
- Patrick ME, et al. Monitoring the Future Panel Study Annual Report: National data on substance use among adults ages 19 to 65, 1976-2023; Available at: https://monitoringthefuture.org/wp-content/uploads/2024/07/mtfpanel2024.pdf. Published July 2024. Accessed Aug. 8, 2024.
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