Role of human papillomaviruses in the development of non-melanoma skin cancers

SUMMARYNonmelanoma skin cancers, which include squamous cell carcinoma and basal cell carcinoma, represent the most frequent cancers among the Caucasian population worldwide. Epidemiological and molecular studies implicate that ultraviolet radiation plays a central role in the development of these cancers.The possibility that certain types of HPV, either alone or in conjunction with ultraviolet radiation, may play a role in the pathogenesis of these cancers is suggested by several studies. Polymerase chain reaction (PCR) based HPV detection techniques have shown a high prevalence of HPV DNA, particularly in skin cancers from immunosuppressed patients and to lesser extend in malignancies from immunocompetent individuals. In these studies, the frequency and spectrum of HPV types detected in nonmelanoma skin cancers varies greatly depending on the differences in the specificities and sensitivities of the PCRprimers used.To evaluate the presence of various types of HPV in nonmelanoma skin cancer lesions of immunocompetent patients, specimens from nonmelanoma skin cancers and normal skin biopsies from gluteal regions of 32 immunocompetent patients were analysed for presence of HPV DNA by a PCR using degenerate primers which can detect a broad spectrum of HPV types. HPV DNA was detected neither in lesional nor normal skin samples. It was thought that in addition to factors associated with Turkish population, these lesions did not harbour HPV DNA or although tissues harbour HPV DNA, it was not detected with thetechnique we used because of low viral load.Ultraviolet radiation may facilitate the growth of HPV by causing local immunosuppression or stimulation of HPV. It was concluded that the reason for absence of HPV DNA in control skin samples, which was taken from gluteal region, might be due tounexposure of this site to ultraviolet radiation and HPV.As a result we could not show the presence of HPV in nonmelanoma skin cancers by using degenerate PCR technique. Studies with more patients and using more sensitive detection techniques which will be developed in the future are needed to show a significant association between HPV and nonmelanoma skin cancer development.