It is estimated that approximately 90% of all head and neck cancers are squamous cell carcinomas with a complex and multifactorial etiology. Molecular and epidemiological studies provide evidence for the role of oncogenic viruses in the initiation and/or oncomodulation of head and neck squamous cell carcinoma. Objectives: The present study aimed to detect the presence of high- and low-risk HPV, BKPyV, EBV, HCMV, HSVs in biopsy samples of squamous cell carcinoma of the external auricle in patients in Bulgaria. Materials and Methods: The study included 41 biopsy specimens from etiologically undiagnosed cases of squamous cell carcinoma of the external auricle. Molecular biological methods were used to detect the viruses—conventional and nested PCR, and sequence analysis. Results: The results obtained showed that none of the samples were found to have a high-risk HPV genotype. The highest percentage of samples showed genotype 6/11, and the lowest number of samples showed low-risk genotype 44. Of all herpesviruses, EBV was found in the largest proportion of samples, being present in the sample as a co-infection with HPV and always together with genotype 6/11. The frequency distribution, as a percentage and number of samples, of the possibilities for co-infection of EBV with each of the HPV genotypes was established. Of the remaining herpesviruses, the presence of HSV 2 was not confirmed in any of the samples. HSV 1 was present in only three of the samples, as a co-infection with genotypes 6/11, 42 and 43. When examining the samples for the presence of HCMV, only one positive sample was found, with both HPV 6/11 and 42 additionally present in the sample. Conclusions: For the first time, HPV, BKPyV, EBV, HCMV and HSVs were investigated and their possible involvement alone or as co-infection in the carcinogenesis of squamous cell carcinoma of the external auricle in patients in Bulgaria. The presence of the mentioned viruses, as well as the non-random distribution of EBV + HPV 6/11 and EBV + HPV 44, proven by us, does not necessarily make them etiological agents, but they could, through different and known mechanisms, influence the initiation and/or modulation of carcinogenesis.
Shishkova et al. (Thu,) studied this question.