Study: Marijuana use increases the risk of head and neck cancer

Here’s some sobering news for stoners.

A new study from the University of Southern California shows that frequent, heavy smoking of marijuana can increase the risk of head and neck cancer.

Marijuana users are 3.5 to 5 times more likely to develop head and neck cancer than people who abstain from smoking joints, according to a study published Thursday in JAMA Otolaryngology–Head & Neck Surgery.

“This is one of the first studies – and the largest to date – to link head and neck cancer to cannabis use,” said Dr. Niels Kokot, head and neck surgeon at the USC Head and Neck Center and senior author of the study. “Recognizing this risk factor is important because head and neck cancer may be preventable if people know what behaviors increase their risk.”

HNCs, which include cancers of the larynx, thyroid, saliva, nose, and sinus, account for nearly 3% of all cancer diagnoses and more than 1.5% of all cancer deaths in the United States.

Marijuana is now the most widely used illegal substance at home and abroad, with consumption increasing steadily over the past decade.

HNCs have been linked in the past to excessive alcohol consumption and cigarette smoking. People who consume both have a higher risk of developing these cancers than people who consume them separately.

The USC researchers found that studies examining the link between cannabis and HNC risk produced inconsistent results. For their study, they analyzed data from 116,000 marijuana smokers.

They concluded that marijuana may be more dangerous than cigarettes.

Cannabis contains similar carcinogens as tobacco products, but smoking marijuana can cause more inflammation in the body.

“Compared to smoking tobacco, smoking cannabis may be even more pro-inflammatory. Cannabis is typically smoked unfiltered and consumed through deeper breaths than tobacco,” they wrote in their findings. “In addition, cannabis burns at a higher temperature than tobacco, increasing the risk of inflammatory injury.”

Although the evidence suggests a link between HNCs and cannabis, the researchers acknowledge that their study has limitations, including a lack of information on dosage, frequency and method of marijuana use.

Northwell Health’s Dr. Michael Blasco, director of the division of head and neck oncology and reconstruction at Staten Island University Hospital, said while the study shows a possible link between cannabis and HNCs, it still leaves questions unanswered, particularly about methodology.

“Is there a difference between patients who use, for example, edibles, gummy bears or brownies, and those who smoke it? And if they smoke it, how do they smoke it? Or do they vape it?” wondered Blasco, who was not involved in the research.

“I would say we know in general that there is a link with cannabis to head and neck cancer, but we don’t know where the safe limit is or if there is one,” he added. “And we don’t know if there is a safe way to use it.”

The USC researchers say future studies examining this link should include “more detailed data on cannabis use.”