According to numerous reports the incidence for oropharyngeal cancer is increasing, and human papillomavirus (HPV) is a risk factor. However, few studies have investigated the specific subsites of the oropharynx. Following their previous research on tonsillar cancer, Attner, et al assessed the increase in the incidence of base of tongue cancer and the prevalence of HPV in this disease. The study took place between 1998 and 2007 and involved 109 patients who were diagnosed for base of tongue cancer in Stockholm county, Sweden. The researchers obtained 95 paraffin-embedded diagnostic tumor biopsies from patients and tested them for HPV. Expression of HPV-16 RNA was analyzed to confirm E6 and/or E7 expression. According to incidence data from the Swedish Cancer Registry, an overall increase in the incidence of base of tongue cancer from 2005 to 2007 were found to be 0.15/100,000 person-years during 1970 to 1974 to 0.47/100,000 person-years. The prevalence of HPV in base of tongue cancer in Stockholm county increased from 58% during 1998 to 2001 to 84% during 2004 to 2007 (P < .05). In the HPV-positive tumors, HPV-16 dominated (86%) but HPV33 was detected in as many as 10%. E6 and/or E7 RNA were found in 85% of the samples tested. The incidence of base of tongue cancer, as well as the proportion of HPV-positive tumors, has increased in Sweden during the study period. This suggests that HPV may contribute to this increase.
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