Study: Daily marijuana use may raise risk of head, neck cancers

A recent study has found that daily use of marijuana for years may increase the risk of head and neck cancers by 3.5 to 5 percent.

The research — published on Thursday in JAMA Otolaryngology-Head & Neck Surgery — analysed a database of four million electronic health records from April 2004 to April 2024.

Niels Kokot, the senior study author and a professor of clinical otolaryngology-head and neck surgery at the Keck School of Medicine at the University of Southern California (USC) in Los Angeles, said they found more than 116,000 diagnoses of cannabis use disorder among people with head and neck cancers.

The diagnoses, according to the research, were based on self-reported use of the drug. It means the patient discussed with a healthcare provider how often they used cannabis and how it affected them.

Cannabis use disorder is when a person has two or more symptoms like desiring weed, using marijuana even though it causes problems in life, experiencing withdrawal, and being unable to quit among others.

Kokot said they also discovered that heavy cannabis users were between 3.5 and 5 times more likely to develop head and neck cancers than those who didn’t use the drug regularly.

Head and neck cancers include cancers of the oral and nasal cavities, pharynx, larynx, salivary glands and thyroid.

Kokot said he and his team used information from patients from 64 health centers in the United States.

“Our research shows that people who use cannabis, particularly those with a cannabis use disorder, are significantly more likely to develop head and neck cancers compared to those who do not use cannabis,” he said.

“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.

“The detection of this risk factor is important because head and neck cancer may be preventable once people know which behaviors increase their risk.”

The researchers said the concern lies with the chemical in marijuana called Tetrahydrocannabinol which can fasten the growth of cancer tumors.

“Part of the research we have already published shows that THC or THC-like compounds can certainly accelerate tumor growth,” Joseph Califano, the study co-author added.

“We also have some data to show that cannabinoids enhance the growth of HPV-related throat cancers.”

The study, however, found no association between the occasional recreational use of marijuana and head and neck cancer.

Previous studies have suggested that marijuana intake can raise risks of heart problems and affect the ability to think.