A recent study published in JAMA Otolaryngology-Head & Neck Surgery has found that regular heavy marijuana use may increase an individual's risk of developing certain types of head and neck cancers. The research, which utilized 20 years of data from a global database called TriNetX, revealed that heavy cannabis users were 3.5 to 5 times more likely to develop these cancers compared to those who did not use the drug regularly.
Head and neck cancers, which include cancers of the mouth, throat, and nasal cavity, are twice as common in men than in women, according to the Centers for Disease Control and Prevention. The study's findings contribute to a growing body of evidence exploring the potential impact of cannabis on cancer risk.
Dr. Niels Kokot, the lead study author and a head and neck surgeon at Keck Medicine of the University of Southern California, suggested that the increased risk could be attributed to the carcinogenic properties of cannabinoids themselves or the smoke produced by cannabis use.
The study analyzed data from over 4 million people, of which approximately 116,000 had been diagnosed with cannabis use disorder between April 2004 and April 2024. The diagnoses were based on self-reported use of the drug, requiring patients to disclose the frequency and impact of their cannabis use to a healthcare provider. The majority of individuals with cannabis use disorder in the study were white and had no prior history of head and neck cancer.
The researchers found that cannabis users were more likely to develop all types of head and neck cancer, except hypopharyngeal cancer, compared to nonusers. The most common types of head and neck cancer in both groups were oral cancers and cancer of the larynx.
However, the study authors acknowledged several limitations that could potentially skew the findings. The reliance on self-reported data made it challenging to accurately measure the number of regular cannabis users. Additionally, the study looked at head and neck cancer diagnoses at two specific time points: within the first year of being diagnosed with cannabis use disorder and five years or beyond the diagnosis. It excluded, however, cancers found one to four years after a cannabis use disorder diagnosis. This secondary analysis was used to determine the strength of the association, with the expectation that if the increased risk remained after five years, it would suggest a stronger association.
Dr. Joseph Califano, director of the Gleiberman Head and Neck Cancer Center at the Moores Cancer Center at the University of California, San Diego, who was not involved in the research, emphasized the difficulty in obtaining reliable data on cannabis use. He noted that the study links the increased risk to self-reported heavy users, equivalent to smoking about a joint per day, rather than occasional users.
The role of dose, frequency, and method of cannabis ingestion in affecting cancer risk remains unclear. Dr. Glenn Hanna, a medical oncologist at the Dana-Farber Cancer Institute's Center for Head and Neck Oncology, suggested that smoking cannabis could activate inflammatory pathways involved in cancer formation, while cannabinoids themselves might become carcinogenic in the body. However, he acknowledged that it is difficult to tease out other risk factors, such as alcohol and tobacco use, as about 20% of the people in the study with cannabis use disorder reported frequent tobacco and alcohol use, compared to only 2% in the group without cannabis use disorder.
Hanna noted that edible cannabis might be safer than smoking the plant, keeping in mind that some of his patients use medical marijuana for health conditions. However, Califano suggested that there's reason to suspect some cannabinoids themselves, rather than the smoke, might be behind the increased cancer risk, if future research establishes a clear connection. He explained that cannabinoids have various effects on immune response and other factors involved in cancer development or the body's ability to fight cancer.
Both Hanna and Califano acknowledge that cannabis likely has both positive and negative effects on health. As research uncovers more about the impact of cannabis on the body, it is probable that different cannabinoids will be found to have different effects on cancer risk, with some potentially associated with cancer development and others inhibiting it.
The study's findings underscore the importance of a cautious approach to cannabis use and the need for individuals to be aware of the potential risks associated with heavy consumption. As research in this field advances, it will be crucial to gain a more comprehensive understanding of the relationship between cannabis use and cancer risk to inform public health policies and individual decision-making.
Head and neck cancers, which include cancers of the mouth, throat, and nasal cavity, are twice as common in men than in women, according to the Centers for Disease Control and Prevention. The study's findings contribute to a growing body of evidence exploring the potential impact of cannabis on cancer risk.
Dr. Niels Kokot, the lead study author and a head and neck surgeon at Keck Medicine of the University of Southern California, suggested that the increased risk could be attributed to the carcinogenic properties of cannabinoids themselves or the smoke produced by cannabis use.
The study analyzed data from over 4 million people, of which approximately 116,000 had been diagnosed with cannabis use disorder between April 2004 and April 2024. The diagnoses were based on self-reported use of the drug, requiring patients to disclose the frequency and impact of their cannabis use to a healthcare provider. The majority of individuals with cannabis use disorder in the study were white and had no prior history of head and neck cancer.
The researchers found that cannabis users were more likely to develop all types of head and neck cancer, except hypopharyngeal cancer, compared to nonusers. The most common types of head and neck cancer in both groups were oral cancers and cancer of the larynx.
However, the study authors acknowledged several limitations that could potentially skew the findings. The reliance on self-reported data made it challenging to accurately measure the number of regular cannabis users. Additionally, the study looked at head and neck cancer diagnoses at two specific time points: within the first year of being diagnosed with cannabis use disorder and five years or beyond the diagnosis. It excluded, however, cancers found one to four years after a cannabis use disorder diagnosis. This secondary analysis was used to determine the strength of the association, with the expectation that if the increased risk remained after five years, it would suggest a stronger association.
Dr. Joseph Califano, director of the Gleiberman Head and Neck Cancer Center at the Moores Cancer Center at the University of California, San Diego, who was not involved in the research, emphasized the difficulty in obtaining reliable data on cannabis use. He noted that the study links the increased risk to self-reported heavy users, equivalent to smoking about a joint per day, rather than occasional users.
The role of dose, frequency, and method of cannabis ingestion in affecting cancer risk remains unclear. Dr. Glenn Hanna, a medical oncologist at the Dana-Farber Cancer Institute's Center for Head and Neck Oncology, suggested that smoking cannabis could activate inflammatory pathways involved in cancer formation, while cannabinoids themselves might become carcinogenic in the body. However, he acknowledged that it is difficult to tease out other risk factors, such as alcohol and tobacco use, as about 20% of the people in the study with cannabis use disorder reported frequent tobacco and alcohol use, compared to only 2% in the group without cannabis use disorder.
Hanna noted that edible cannabis might be safer than smoking the plant, keeping in mind that some of his patients use medical marijuana for health conditions. However, Califano suggested that there's reason to suspect some cannabinoids themselves, rather than the smoke, might be behind the increased cancer risk, if future research establishes a clear connection. He explained that cannabinoids have various effects on immune response and other factors involved in cancer development or the body's ability to fight cancer.
Both Hanna and Califano acknowledge that cannabis likely has both positive and negative effects on health. As research uncovers more about the impact of cannabis on the body, it is probable that different cannabinoids will be found to have different effects on cancer risk, with some potentially associated with cancer development and others inhibiting it.
The study's findings underscore the importance of a cautious approach to cannabis use and the need for individuals to be aware of the potential risks associated with heavy consumption. As research in this field advances, it will be crucial to gain a more comprehensive understanding of the relationship between cannabis use and cancer risk to inform public health policies and individual decision-making.
