Frequent marijuana users may face a significantly higher risk of developing head and neck cancers, according to a new study by the University of Southern California (USC).
The study, published in JAMA Otolaryngology – Head & Neck Surgery, found that individuals who smoke marijuana regularly are between 3.5 and 5 times more likely to develop head and neck cancers (HNCs) compared to those who do not use the drug.
These findings bring a new layer of concern to the ongoing debate about the health effects of marijuana, which is the most commonly used illicit substance worldwide.
“This is one of the first studies — and the largest that we know of to date — to associate head and neck cancer with cannabis use,” said Dr. Niels Kokot, a head and neck surgeon at Keck Medicine of USC and the senior author of the study.
He highlighted the importance of recognizing this risk, noting that awareness could lead to preventive measures against these types of cancers.
HNCs, which include cancers of the oral and nasal cavities, pharynx, larynx, salivary glands, and thyroid, represent nearly 3% of all cancer diagnoses in the United States and account for more than 1.5% of cancer-related deaths.
While previous research has linked these cancers to excessive alcohol consumption and tobacco use, the connection with marijuana use had not been firmly established until now.
The USC researchers analyzed medical data spanning 20 years from 116,000 individuals, comparing those who reported heavy marijuana use with non-users who shared similar health characteristics.
The results indicated that marijuana could be more hazardous than tobacco in terms of HNC risk, primarily due to the differences in how the substances are consumed.
Unlike tobacco, marijuana is typically smoked without filters and inhaled more deeply, which could lead to greater inflammatory injury.
Moreover, cannabis burns at a higher temperature than tobacco, potentially increasing the risk of damage to the tissues of the head and neck.
Despite the study’s significant findings, the researchers acknowledged several limitations. The study did not provide detailed information on the dosage, frequency, or method of marijuana use, which could affect the level of risk.
Dr. Michael Blasco, director of head and neck oncology at Staten Island University Hospital, who was not involved in the research, raised concerns about these gaps. He questioned whether different methods of cannabis consumption, such as edibles or vaping, might present varying levels of risk compared to smoking.
“I would say, in general, we know that there’s a link between head and neck cancer now in cannabis, and we don’t know what the safe threshold is or if there even is one,” Dr. Blasco commented. He also noted the need for further research to determine whether any method of marijuana use could be considered safe.
The USC researchers called for more comprehensive studies that would include detailed data on cannabis use, to better understand the full scope of the risks involved.
As marijuana use continues to rise, especially with the growing trend of legalization across various states, understanding these risks is becoming increasingly important.
For now, the study’s findings serve as a cautionary tale for marijuana users, highlighting a potential health risk that has not been widely recognized.