Etiological Role of Human Papillomavirus Infection in the Development of Penile Cancer.

BACKGROUND AND AIMS: To examine an association between human papillomavirus (HPV) infection and penile cancer among Japanese patients.

METHODS: Thirty-four patients with penile cancer were enrolled in this study. DNA was extracted from paraffin-embedded tumor-tissue samples, and HPV-DNA tests and genotyping were performed. In all of samples, in situ hybridization (ISH) was performed to locate HPV-DNA in tumor tissue; expression levels of p16-INK4a, mini-chromosome maintenance protein-7(mcm-7), HPV-L1, and Ki-67 were analyzed using immunohistochemical methods.

RESULTS: HPV and high-risk (HR)-HPV were detected in 14 (41.2%; 95% confidence intervals [CI], 24.6-57.7%) and 12 (35.2%; 95%CI, 19.2-51.4%) cases, respectively. HPV16 was the most frequently detected HPV type. Among the HR-HPV-positive cases, a punctate HR-HPV-DNA signal pattern was detected by ISH in tumor-cell nuclei. P16-INK4a expression was expressed in 66.7% (95%CI, 42.8-90.1%) of HR-HPV positive-cases, and was significantly frequent and stronger in HR-HPV-positive cases than in HPV-negative cases. There were no significant differences in the occurrence and distribution of mcm-7 and Ki-67 expression between HPV-positive and HPV-negative cases. HPV-L1 expression was not observed in any of the examined cases.

CONCLUSIONS: HPV infection may have had an etiological role in 41% examined cases of penile cancer in Japan.