According to a new study, cannabis use may be linked to an increased risk of head and neck cancer.

The study, published on August 8 in the journal JAMA Otorhinolaryngologysuggests that people with cannabis use disorder are more likely to develop cancer of the mouth, oropharynx, and larynx than people without the disorder.

Although there is limited data on cannabis use in the United States, the Centers for Disease Control and Prevention estimates that an estimated 30% of cannabis users have cannabis use disorder. A person may be diagnosed if cannabis use interferes with their ability to function normally, or if they have a craving for cannabis, use more than intended, and try to stop using it but are unable to do so.

The study suggests that this condition may be associated with a higher risk of head and neck cancer, which accounts for 4% of all cancers in the United States. However, researchers cannot say with certainty whether cannabis consumption actually increases the risk of developing these types of cancer.

“This study suggests there is a connection, but we don’t yet know how big it is,” Dr. Niels Kokot, 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 cancer, and what the study’s results might mean for you.

The aim of the study was to determine whether heavy cannabis use is associated with the risk of head and neck cancer, which can occur in the mouth, nose, sinuses, salivary glands, throat and larynx.

“Other studies have attempted to demonstrate a link between (the two) but have failed 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 medical records of over four million people in the United States. They found that 116,076 of them had been diagnosed with cannabis use disorder. This group was roughly equally divided between men and women, and their average age was 46.

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

The new study appears to contradict previous research that suggested cannabis could reduce the risk of certain cancers – although most of those studies were conducted in the laboratory, said Luc Morris, MD, a head and neck surgeon at Memorial Sloan Kettering Cancer Center Health.

“I think the research on reducing cancer risk that people are referring to is mostly preclinical, not in humans,” he said. “I can say with confidence that there is no evidence that cannabis reduces cancer risk.”

Some experts have theorized that cannabis use might increase the risk of head and neck cancer in the same way that tobacco smoking does. But “that’s all speculation,” Morris said. No one knows exactly how cannabis use might increase the likelihood of developing these cancers, he added.

While Kokot said research shows there is “some risk” associated with heavy cannabis use, the study also has some limitations.

A major problem is that the researchers didn’t have much information about the participants, Kokot said. They only knew whether the participants had been diagnosed with cannabis use disorder – not how long they had been using cannabis or to what extent. Given this, it’s impossible to say at what point cannabis use begins to affect a person’s risk of head and neck cancer, making it difficult to determine the extent to which this research is applicable to the general population.

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

It’s also possible that cannabis itself does not increase the risk of head and neck cancer, but that cannabis users are more likely to engage in activities that have been shown to increase risk, such as smoking and heavy alcohol consumption, Morris added. “We don’t know if cannabis causes the cancer,” he said.

According to Morris, diet, exercise and oral hygiene all play a role in a person’s risk of developing head or neck cancer, as do social determinants of health, such as access to doctors and income level.

Given this uncertainty, Morris says not everyone should feel compelled to give up cannabis use just yet, especially if it relieves pain or other problems.

“I would be concerned if people (mis)interpreted this study,” he said, adding that he would “feel bad” if someone with a chronic illness who gets significant relief from cannabis felt they should now avoid it. “We still don’t have good evidence that it promotes cancer growth,” he said.

If you are concerned about your cannabis use, it is best to talk to a doctor about what effects it may have on your health, experts say.