A recent study has revealed that consistent daily marijuana smoking over several years may raise the risk of head and neck cancers by 3.5% to 5%.
According to CNN, this research, which analyzed millions of medical records, underscores the potential health risks associated with cannabis use.
The National Cancer Institute reports that approximately 69% of individuals diagnosed with oral or throat cancer survive for five years or more. However, if the cancer spreads, the survival rate drastically decreases to 14%.
Tobacco use, encompassing cigarettes, cigars, pipes, and smokeless tobacco, along with alcohol consumption, remains the leading cause of head and neck cancers, according to experts.
Other contributing factors include poor oral hygiene, gastroesophageal reflux disease, a weakened immune system, and a diet deficient in fruits and vegetables. Occupational exposure to hazards like asbestos and wood dust also plays a role.
The study’s senior author and a professor of clinical otolaryngology-head and neck surgery at the Keck School of Medicine at the University of Southern California, Dr. Niels Kokot, commented, “Our research indicates that individuals who use cannabis, especially those with cannabis use disorder, are significantly more likely to develop head and neck cancers compared to those who do not use cannabis.”
Cannabis use disorder is diagnosed when a person exhibits two or more symptoms, such as craving marijuana, developing tolerance, using more than intended, continuing use despite life problems, consuming marijuana in high-risk situations, experiencing withdrawal, and being unable to quit, as outlined by the US Centers for Disease Control and Prevention.
For laryngeal cancer, the five-year survival rate is 61%, which drops to 16% if the cancer spreads.
“While our study did not distinguish between different methods of cannabis consumption, smoking is the most common way cannabis is consumed,” Kokot noted in an email. “The association we found likely pertains mainly to smoked cannabis.”
The study used insurance data to examine the link between cannabis use disorder and head and neck cancers.
Dr. Joseph Califano, who was not involved in the research but serves as the Iris and Matthew Strauss Chancellor’s Endowed Chair in Head and Neck Surgery at the University of California, San Diego, and the director of UC San Diego’s Hanna and Mark Gleiberman Head and Neck Cancer Center, praised the research, saying, “The researchers analyzed a vast dataset, which is quite remarkable, and there is significant power in examining such large numbers, particularly since we often only have smaller studies.”
Califano, who co-authored an editorial accompanying the study in, JAMA Otolaryngology–Head & Neck Surgery*, emphasized that the study does not imply a link between “occasional recreational use of marijuana and head and neck cancer.”
Experts suggest that similar to tobacco, smoking marijuana may elevate the risk of head and neck cancers. In the U.S., these cancers account for 4% of all cancer cases, with more than 71,000 new cases and over 16,000 deaths expected in 2024, according to the National Foundation for Cancer Research.
An increasing number of head and neck cancers are linked to infections with the human papillomavirus and the Epstein-Barr virus, both DNA viruses known to influence genes and contribute to malignancies.
The Epstein-Barr virus is associated with infectious mononucleosis, often referred to as the “kissing disease,” and several types of cancers. It is estimated that 90% of the global population is infected with EBV. A vaccine exists for HPV, which is linked to a high risk of cervical cancer and certain non-Hodgkin lymphomas.
It is possible to be simultaneously infected with both viruses, a combination responsible for 38% of all virus-related cancers, according to research.
The study, published in JAMA Otolaryngology–Head & Neck Surgery, reviewed a database containing 4 million electronic health records and identified over 116,000 diagnoses of cannabis use disorder among individuals with head and neck cancers.
These patients, with an average age of 46, were compared to those with head and neck cancers who did not have cannabis use disorder.
The analysis found that individuals with cannabis use disorder were about 2.5 times more likely to develop oral cancer, nearly five times more likely to develop oropharyngeal cancer, affecting the soft palate, tonsils, and back of the throat, and more than eight times more likely to develop laryngeal cancer. These findings were consistent across all age groups.
Experts believe that the increased cancer risk associated with smoking weed is largely due to smoke inhalation. Smoking tobacco, for example, doubles the risk of developing head and neck squamous cell carcinoma, which constitutes 90% of all head and neck cancers.
The risk is higher with more frequent tobacco use, especially when combined with alcohol.
Given how marijuana is typically smoked—unfiltered, deeply inhaled, and held in the lungs and throat for several seconds—experts warn that the risk from cannabis smoke could be even greater.
Another factor connecting cannabis to cancer is the role of cannabinoids in tumor growth.
The National Center for Complementary and Integrative Health notes that cannabis contains over 100 cannabinoids, compounds that bind to cannabinoid receptors in the human body. The marijuana plant has about 540 chemicals in total.
Tetrahydrocannabinol, THC, is the compound responsible for marijuana’s euphoric effects, while cannabidiol, CBD, has shown medicinal benefits for conditions like childhood seizures and epilepsy.
“Some of the research we have already published shows that THC or THC-like compounds can certainly accelerate tumor growth,” Califano said. “We also have some data suggesting that cannabinoids may enhance the growth of HPV-related throat cancers.”
As marijuana use continues to rise, there is growing concern that head and neck cancer diagnoses may increase in the future, Kokot warned.
“As cannabis becomes more widely legalized and socially accepted, we may see a corresponding rise in head and neck cancer cases if this association is confirmed,” he said. “This highlights the importance of informing the public about potential risks and conducting further research to understand the long-term impacts of cannabis use on cancer development.”
