Heavy Cannabis Use May Increase the Risk of Head and Neck Cancers

Using cannabis may be tied to an increase in the risk of head and neck cancers, a new study has found.¹

The research, published August 8 in the journal JAMA Otolaryngology-Head and Neck Surgery, suggests that people with cannabis use disorder are more likely than those without the disorder to develop oral, oropharyngeal, and laryngeal cancers.

Though data on cannabis use in the United States is limited, the Centers for Disease Control and Prevention says that an estimated 30% of cannabis users have cannabis use disorder. A person may be diagnosed with the disorder if cannabis use affects their ability to function normally or if they crave cannabis, use more of it than intended, and try but fail to quit using it.² 

The study indicates that having this disorder may be linked to a higher risk of head and neck cancers, which make up 4% of all cancers in the U.S.³ But the researchers can’t say definitively whether cannabis use actually raises the risk of developing these cancers.

“What this study indicates is that there is an association, but we don’t know yet how much,” Niels Kokot, MD, study author and head and neck surgeon at Keck Medicine of USC, told Health. 

Here’s what the research adds to our understanding of the relationship between cannabis and head and neck cancers, as well as what the study’s findings might mean for you.

How Cannabis Use May Influence the Risk of Head and Neck Cancers

The study authors set out to clarify whether heavy cannabis use has any connection to the risk of head and neck cancers, which can develop in the mouth, nose, sinuses, salivary glands, throat, and larynx (voice box).

“Other studies tried to show an association between [the two] but were unable to do so” due to study limitations, Kokot explained.

For the study, Kokot’s team relied on medical records from TriNetX, a global database that contains data on millions of people.

The researchers examined the records of over four million people in the U.S. They found that 116,076 of them had received a diagnosis of cannabis use disorder. That group included a roughly equal number of men and women, and their average age was 46.

After crunching the numbers, the team discovered that people with cannabis use disorder were more likely to develop head and neck cancers. The rate of oral cancer among people in this group was more than double that of the control group, while the rate of oropharyngeal cancers was almost five times as high, and the rate of laryngeal cancers was more than eight as high.

The new study appears to counter previous research suggesting that cannabis may reduce the risk of certain cancers—though most of those studies have been conducted in laboratory settings, Luc Morris, MD, a head and neck surgeon at Memorial Sloan Kettering Cancer Center, told Health.

“I think the research for decreased risk of cancer that people reference is largely preclinical, meaning not in humans,” he said. “I do feel comfortable saying there’s no evidence that cannabis reduces the risk of cancer.”

As for why the opposite might be true, some experts have theorized that cannabis use may increase the risk of head and neck cancers in the same way that smoking tobacco does. But “that’s all speculative,” Morris said. No one knows precisely how cannabis use might raise the odds of developing these cancers, he added.

What This Means for Cannabis Users

While Kokot said the research shows “there is some risk” when it comes to heavy cannabis use, the study does have some limitations.

A major one is that researchers didn’t have much information about the participants, Kokot said. All they knew was whether people had been diagnosed with cannabis-use disorder—not how long they had used cannabis or to what extent. Given that, it’s impossible to say at what point cannabis use may start to influence a person’s risk of head and neck cancer, making it difficult to determine how applicable this research is to the general population.

“More research is needed to determine the type of use and the amount of use that is the true risk for head and neck cancer,” Kokot said.

It’s also possible that cannabis itself doesn’t raise the risk of head and neck cancers but that people who use cannabis are more likely to engage in activities that have been proven to increase risk, such as smoking and heavy drinking, Morris added. “We don’t know if it’s the cannabis that’s causing the cancer,” he said.

Diet, exercise, and oral hygiene also all play a role in a person’s risk of developing head and neck cancer, as do social determinants of health, like access to doctors and income level, Morris said.

Given the uncertainty, Morris said that not everyone should feel compelled to stop using cannabis just yet, especially if it helps alleviate pain or other issues.

“I would worry about people interpreting this study [incorrectly],” he said, adding that he’d “feel bad” if someone with a chronic illness who gets significant relief from cannabis felt like they should now avoid it. “We still don’t have good evidence that it promotes cancer growth,” he said.

If you’re worried about your cannabis habits, it’s best to speak to a doctor about how they might affect your health, experts said.