Detection of human papillomavirus (HPV) DNA in oral squamous cell carcinomas by in situ hybridization and polymerase chain reaction.

A series of 156 formalin-fixed, paraffin-embedded biopsies from 40 patients with surgically-treated oral squamous cell carcinomas was analysed for the presence of human papillomavirus (HPV) infection by histopathological evaluation, in situ DNA hybridization and polymerase chain reaction (PCR). Epithelial changes suggesting a HPV lesion within, or adjacent to, the carcinoma lesions were found in 16 out of 40 patients (40%). Morphological signs of a flat HPV lesion were found in four cases (10%), those of inverted type in three cases (7.5%), and those of papillary type in nine cases (22.5%). HPV DNA was demonstrated in one of the lesions by in situ hybridization with biotin-labelled DNA cocktail probe containing HPV types 6, 11, 16 and 18. With the PCR technique, samples from 11 (27.5%) of the 40 patients proved to contain HPV DNA. Of these, HPV 6 was demonstrated in one case, HPV 16 in ten cases and HPV 18 in one case. HPV DNA was exclusively detected in the biopsies showing carcinoma tissue or its adjacent precancer lesions. No viral DNA was found in the biopsies derived from the tumour-free resection margins. These results provide further evidence to support the concept of HPV involvement in the aetiology of oral squamous cell carcinomas, most probably acting synergistically with other carcinogens.