Human papillomavirus as a risk factor in oral carcinogenesis: a study using in situ hybridization with signal amplification

Introduction:  It is still controversial whether human papillomavirus (HPV) can be considered a risk factor in oral carcinogenesis. The aim of this study was to detect HPV DNA in 50 cases diagnosed as oral leukoplakias, with different degrees of epithelial dysplasia, and as oral squamous cell carcinomas, using in situ hybridization with signal amplification (CSA-ISH).
Methods:  HPV DNA was assessed in paraffin sections using CSA-ISH with a wide-spectrum biotinylated DNA probe. In HPV-positive cases, genotyping with specific probes to HPV types 6/11, 16/18 and 31/33 was performed.
Results:  The overall prevalence of HPV infection was 24%, markedly higher than that found in the control group. Results showed a discrete proportional relationship in the indices found in leukoplakia with no dysplasia, leukoplakia with dysplasia, and squamous cell carcinoma, but this was not statistically significant. When separating the group of leukoplakia by degrees of dysplasia, this relation of proportion was not observed. In genotyping, HPV types 16/18 were the most prevalent, and types 6/11 were only found in groups of mild or no dysplasia.
Conclusion:  The results suggest that HPV is not likely to play a role in the progression of malignant transformation in oral lesions. Nevertheless, the increased prevalence of HPV infection compared to normal oral mucosa and the fact that high-risk HPV types were the most frequently identified do not allow the exclusion of HPV as a risk factor in oral carcinogenesis.