Prevalence of human papillomavirus in mobile tongue cancer with particular reference to young patients.

The carcinogenetic role of human papillomavirus (HPV) in mobile tongue cancer remains unclear because of conflicting results reported in the literature. This disparity is likely to be due to variations in the samples and methods used. Furthermore, despite a tendency for increased prevalence of mobile tongue cancer in young adults, only a few reports specifically in young patients have been published. In the present study on 32 patients, including six in their 20s, we genotyped the prevalence of HPV using a highly sensitive detection tool in fresh-frozen samples from surgical specimens and a novel detection device with electrochemical DNA chip and loop-mediated isothermal amplification. In addition, we confirmed HPV prevalence by in situ hybridization and immunohistochemistry for the p16(INK4a) protein, regarded as a biomarker of HPV-associated cancers. The frequency of 13 genotypes of high-risk HPV was 0/32 (0%), which was further confirmed by in situ hybridization. Overexpression of p16(INK4a) protein was observed in six of the 32 patients (19%), with four (67%) also overexpressing p53. Because there is usually a lack of p53 overexpression in HPV-associated cancer, it is unlikely that p16(INK4a) protein overexpression is correlated with HPV infection. Consequently, it is unlikely that HPV infection plays an important role in mobile tongue carcinogenesis, in particular in young adults. In addition, our data suggest that the overexpression of p16(INK4a) protein is not an appropriate biomarker for HPV association in mobile tongue carcinogenesis.