Adapted from the NCI Cancer Bulletin, vol. 4/no. 17, May 15, 2007 (see the current issue).A new epidemiological study led by researchers from Johns Hopkins University implicates human papillomavirus (HPV) exposure and infection as strong risk factors for oropharyngeal cancer (a kind of head and neck cancer). The results from the case-control study, published in the May 10, 2007, New England Journal of Medicine, show that HPV exposure and infection increase the risk of oropharyngeal squamous cell cancer independently of tobacco and alcohol use, two other important risk factors for the disease (see the journal abstract).
The investigators enrolled 100 patients with newly diagnosed oropharyngeal squamous cell carcinoma and 200 control patients in the study. Oral-mucosal and serum samples were collected from all patients. Tumor samples were also collected from case patients. The investigators analyzed all collected samples for presence of HPV DNA or antibodies that would indicate prior exposure. Personal and medical history information collected included oral hygiene history, sexual history, and lifetime use of marijuana, tobacco, and alcohol.
Researchers found that "the presence of an oral HPV 16 infection was strongly associated with oropharyngeal cancer." HPV 16 is one of the two strains of HPV most often associated with cervical cancer. Past exposure to HPV 16, as measured by presence of antibodies to the virus in serum samples, was also strongly associated with oropharyngeal cancer. Antibodies against HPV 16 were found in 64 percent of case patients but only 4 percent of control patients. Data collected on sexual history "suggest that oral HPV infection is sexually acquired…but we cannot rule out transmission through direct mouth-to-mouth contact or other means," said the authors.
A history of heavy tobacco and alcohol use remained a strong risk factor, but "combined exposure to HPV and heavy tobacco and alcohol use was not additive," they explained. "It is important for health care providers to know that people without the traditional risk factors of tobacco and alcohol use can nevertheless be at risk for oropharyngeal cancer," stated first author Dr. Gypsyamber D'Souza in an accompanying press release.