Cannabis-Related Disorders May Increase Head and Neck Cancer Risk, New Study Suggests

The results underscore challenges in cannabis research and call for more studies.

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Daily cannabis use over several years may increase the risk of head and neck cancers up to five times, according to new research that analyzed over 4 million medical records.

The findings come amid ongoing difficulties in studying cannabis effects, including self-reporting inaccuracies and limited funding for comprehensive research.

Cannabis use disorder is defined as experiencing over a period of a year at least two symptoms such as using cannabis in larger quantities or for a longer duration than originally intended, cravings for cannabis use, and recurrent use resulting in neglect of social obligations.

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The study, published in JAMA Otolaryngology-Head & Neck Surgery, shows that people with cannabis-related disorders have a higher risk of oral, oropharyngeal, and laryngeal cancers compared to those without such disorders.

Researchers analyzed data from the US Collaborative network, a global network of electronic health records. The team divided patient records into two groups: those with and without cannabis-related disorders.

After adjusting for other factors, the study found that people with cannabis disorders had higher risks of developing:

• Any head and neck cancer (HNC): 3.49 times higher
• Laryngeal cancer: 8.39 times higher
• Nasopharyngeal cancer: 2.60 times higher
• Oral cancer: 2.51 times higher
• Oropharyngeal cancer: 4.90 times higher
• Salivary gland cancer: 2.70 times higher

There was no significant increase in risk for hypopharyngeal cancer.

When considering only cancers that developed 1 year or more after the cannabis disorder diagnosis:

• The risk for any HNC increased to 4.40 times higher
• Oral cancer risk increased to 3.11 times higher
• Oropharyngeal cancer risk increased to 6.70 times higher
• Laryngeal cancer risk slightly decreased to 7.10 times higher, but remained significant
• Nasopharyngeal and salivary gland cancer risks were no longer significant

For cancers developing 5 years or more after the cannabis disorder diagnosis:

• The risk for any HNC further increased to 5.00 times higher
• Risks for specific HNC types were no longer statistically significant, likely due to smaller sample sizes

One limitation of this study was the follow-up duration with adequate sample size, especially beyond five years post-diagnosis. Other constraints included limited access to long-term records, inconsistent cannabis use among patients, and other uncontrolled factors. Despite these limitations, the authors wrote, associations “remained” between cannabis use and overall head and neck cancer, oral cancer, oropharyngeal cancer, and laryngeal cancer.

Researchers Call for More Studies Amid Rising Use

Head and neck cancers make up almost 4 percent of all cancers in the U.S., according to the National Cancer Institute. These cancers are more than twice as common in men than women and are more frequently diagnosed in people over 50.

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Despite its potential benefits, cannabis use remains controversial, partly due to its ability to cause addictive-like behaviors leading to cannabis-related disorders. The research team defines these disorders as excessive drug use resulting in “associated psychosocial symptoms,” including impaired social or occupational functioning.

The researchers emphasize the need for further studies to better understand the associated risks. The potential link between cannabis use and head and neck cancers has substantial public health implications, given the rising cannabis use among young adults and trends toward legalization.

Given the growing popularity of cannabis, particularly among young adults, and the ongoing legalization efforts, it’s important to conduct more research to fully understand the potential health risks associated with its use, the authors noted.

Currently, cannabis is legal for medical use in 38 states and recreational use in 24 states.

Looking at the bigger picture, the implications of the study are “sobering,” Dr. Joseph Caliafano, and otolaryngologist who specializes in head and neck surgical oncology, wrote in a commentary accompanying the study.

The association between cannabis and head and neck cancer in this study spanned two decades during rapid growth in use, he noted. If this association is causative, the burden of [head and neck squamous cell carcinoma] attributable to cannabis may continue to increase dramatically,” Dr. Caliafano added.