Researchers at the Johns Hopkins Kimmel Cancer Center have found two sets of behavioral risk factors for head and neck cancers, suggesting that there are two different kinds of the disease. Their findings were published in the March 19 issue of Journal of the National Cancer Institute.
Researchers led by Maura L. Gillison, MD, PhD, an associate professor of oncology and epidemiology at The Johns Hopkins University School of Medicine, studied 240 patients who had received diagnoses of head and neck squamous cell carcinomas at The Johns Hopkins Hospital between 2000 and 2006 and determined whether their tumors were linked to human papillomavirus (HPV). Two age- and sex-matched control participants without cancer for every one participant with cancer formed the control group. All study participants completed a computerized interview that asked questions about their risk factors.
Researchers detected HPV in 92 of the participants with cancer. They found that HPV-positive cancers were associated with several measures of sexual behavior and exposure to marijuana but not with tobacco or alcohol use or poor oral hygiene. These associations became stronger with increasing numbers of oral sex partners, as well as with longer or more intense use of marijuana. Participants who smoked marijuana for at least five years but did not smoke tobacco were 11 times more likely to develop HPV-positive cancers.
Dr. Gillison says the study is one of the first to connect marijuana use with the development of HPV-linked head and neck cancers. "It’s possible that other behaviors linked with marijuana use could be the real culprit, and our results will need to be confirmed," she says.
Researchers also found that HPV-negative cancers were associated with tobacco or alcohol use and with poor oral hygiene but not with any measure of sexual behavior or marijuana use. Poor oral hygiene and tobacco and alcohol use are known risk factors for non-HPV–related head and neck cancer. Researchers found that participants who had used tobacco and alcohol heavily were nearly five times more likely to develop HPV-negative head and neck cancers. Participants who brushed their teeth less than once a day were four times more likely to develop HPV-negative tumors.
"Our results indicate that HPV-positive and HPV-negative head and neck cancers have different risk-factor profiles and should be considered two distinct diseases," said Dr. Gillison. "They just happen to occur in the same place."
This study was supported by the Damon Runyon Cancer Research Foundation, the State of Maryland Cigarette Restitution Fund, and the National Institutes of Health, National Institute of Dental and Craniofacial Research.
