Here’s some sobering news for stoners.
Frequent, heavy pot smoking may raise the risk for head and neck cancers, a new University of Southern California study finds.
Marijuana users are between 3.5 and 5 times more likely to develop those cancers, known as HNCs, than those who pass on joints, according to research published Thursday in JAMA Otolaryngology – Head & Neck Surgery.
“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 senior author of the study. “The detection of this risk factor is important because head and neck cancer may be preventable once people know which behaviors increase their risk.”
HNCs, which include cancers of the oral and nasal cavities, pharynx, larynx, salivary glands and thyroid, account for nearly 3% of cancer diagnoses and more than 1.5% of cancer deaths in the US.
Meanwhile, marijuana is “the most commonly used illicit substance worldwide,” per the study, with usage steadily increasing over the past decade.
HNCs have previously been linked to excess alcohol consumption and cigarette smoking, and people who do both are at greater risk of developing these cancers than those who only drink or only smoke.
The USC researchers noted that studies that have explored the association between cannabis and HNC risk have produced inconsistent results.
For their research, they compared the medical data of 116,000 people, divided among marijuana users who had reported to a health professional that they were dependent on pot and non-users with similar health characteristics. The USC researchers analyzed 20 years of this medical data.
They found that pot may prove more hazardous than cigarettes in terms of HRCs, even though cannabis smoke contains carcinogens similar to those found in tobacco products.
“Compared with smoking tobacco, smoking cannabis may be even more pro-inflammatory. Cannabis smoking is typically unfiltered and consumed through deeper breaths than tobacco,” the study authors wrote. “Additionally, cannabis burns at a higher temperature than tobacco, increasing the risk of inflammatory injury.”
While the evidence suggests a relationship between HNCs and cannabis, researchers admit their study has limitations. Among these is a lack of information regarding dosage, frequency and method of marijuana use.
Northwell Health’s Dr. Michael Blasco, the director of head and neck oncology and reconstruction at Staten Island University Hospital, said he has questions about the study.
“Is there a difference in patients that, for example, use edibles or gummies or brownies versus people who smoke it? And if they do smoke it, how are they smoking it? Or are they vaping?” wondered Blasco, who was not involved in the research.
“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,” he added. “And we don’t know if there’s a safe method of using it.”
The USC researchers say future studies that explore this association should include “more thorough data on cannabis use.”
