Invasive Squamous Cell Carcinoma of the Oral Mucosa Associated with HPV Type 53: DISCUSSION

Oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a com­mon cancer whose significant risk factors are smoking, alcohol, betel quid use, sun exposure and immunosuppression. Recently many researchers have suggested that HPV infection is a causative factor of OSCC. While it is well known that HPV infec­tion is a significant risk factor for cervical cancer, its relationship with oral malignant tumors has not been fully characterized yet. In 1985, de Villier first detected HPV DNA in oral carcinoma, and many studies have confirmed this finding. A review of articles from 1982 to 1997 showed that the detection rate of HPV in OSCC was up to 46.5%. The most frequently detected types were HPV 16 and 18, suggesting an important role for these viruses in malignant transformation. Other various types of HPV were detected in oral cancers, although their detection rates were much lower than those of HPV- 16 and 18.

In this study we demonstrated HPV-53 infection in an invasive, oral squamous cell carcinoma. To our knowledge, this is the first report of detection of HPV-53 in a malignant lesion of the oral mucosa. This virus had originally been detected in benign lesions of female genitalia and leukoplakia. Until now, only six cases have been reported in the literature where HPV-53 was isolated from cancer lesions. The specimens were all from cervical squamous cell carcinoma, among which only two were found to have a single infection of that virus.

The other four cases harbored another high-risk HPV type, along with HPV-53. The rarity of reports on HPV-53 in malignant tumors rendered it difficult to define the oncogenic status of the virus. While some researchers classify HPV-53 as a high-risk type , others regard it as not associated with malig­nant transformation. canadian cialis online

In the present study, HPV-53 was the only HPV type isolated from the biopsy specimen. There was no evidence of infection by other HPV types, especially, high-risk types such as HPV-16, 18, 31, 33 or 35. The singular presence of HPV-53 in an invasive OSCC in a patient with no other risk factors, supports the recent suggestion that HPV-53 is a probable high-risk type associated with malignant progression of epithelial lesions. In particular, it was unique that HPV-53 had been isolated from a malignant tumor of the oral cavity such as OSCC, other than from cervical cancer. We tried to determine the HPV status of the previous verrucous carcinoma, but have failed to detect any HPV in that lesion. Further studies on more HPV-53 positive cancers are required to define the oncogenicity of HPV-53.