Merkel Cell Polyoma Virus and Cutaneous Human Papillomavirus Types in Skin Cancers: Optimal Detection Assays, Pathogenic Mechanisms, and Therapeutic Vaccination.

Oncogenic viruses are recognized to be involved in some cancers, based on very well-established criteria of carcinogenicity. For cervical cancer and liver cancer, the responsible viruses are well-known (e.g., HPV, HBV); in the case of skin cancer, there are still many studies which are trying to identify the possible viral etiologic agents as principal co-factors in the oncogenic process. We analysed scientific literature published in the last 5 years regarding mechanisms of carcinogenicity, methods of detection, available targeted therapy, and vaccination for Merkel cell polyomavirus, and beta human papillomavirus types, in relation to skin cancer. This review is targeted at presenting the recent findings which support the involvement of these viruses in the development of some types of skin cancers. In order to optimize the management of skin cancer, a health condition of very high importance, it would be ideal that the screening of skin cancer for these two analysed viruses (MCPyV and beta HPV types) to be implemented in each region's/country's cancer centres' molecular detection diagnostic platforms, with multiplex viral capability, optimal sensitivity, and specificity; clinically validated, and if possible, at acceptable costs. For confirmatory diagnosis of skin cancer, another method should be used, with a different principle, such as immunohistochemistry, with specific antibodies for each virus.