Third of throat cancers linked to HPV infection

Human papillomavirus -- the major cause of cervical cancer -- also infects a third of throat cancer patients, U.S. and British researchers say. Aimee R. Kreimer of the National Cancer Institute, part of the National Institutes of Health, and Ruth C. Travis of University of Oxford, and numerous colleagues in several countries identified 638 study participants. Of the study participants, 180 had oral cancers, 135 oropharynx cancers -- part of the pharynx -- 247 hypopharynx/larynx cancers and 300 patients had esophageal cancers. The study also involved 1,599 controls. There are more than 100 types of HPV and most people recover easily but two strains -- HPV-16 and HPV-18 -- cause most cervical and oral cancers. Prediagnostic plasma samples from patients were collected, on average, six years before diagnosis. Control participants were analyzed for antibodies against multiple proteins of HPV16 as well as HPV6, HPV11, HPV18, HPV31, HPV33, HPV45 and HPV52. At the end of the study period the researchers checked for the presence of antibodies to one of HPV's key proteins, known as E6. The protein disables the cells' protection system that prevents cancer, but detecting the antibodies indicates HPV overcame the defenses. The study, published in the Journal of Clinical Oncology, found 34.8 of those with throat cancer had the antibodies, compared with 0.6 percent of those who were cancer-free. The findings indicated HPV-16 infection might be a significant cause of oropharyngeal cancer, in the middle part of the pharynx, behind the mouth, and includes the back one-third of the tongue, the soft palate, the side and back walls of the throat and the tonsils. Recently, actor Michael Douglas caused a stir when he said throat cancer might be linked to oral sex.