Etiological role of human papillomavirus infection in the development of penile cancer

•Human papillomavirus (HPV) was detected in 41% of patients with penile cancer.•HPV16 was detected most frequently in penile cancer.•In situ hybridization revealed an HPV-DNA punctate signal in the HPV-positive cases.•P16-INK4a expression was significantly stronger in high-risk HPV-positive cases.•mcm-7 and Ki-67 expression had no correlation with HPV status in penile cancer. To examine the association between human papillomavirus (HPV) infection and penile cancer among Japanese patients. 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. For all of the samples, in situ hybridization (ISH) was performed to locate HPV-DNA in tumor tissue. Furthermore, expression levels of p16-INK4a, mini-chromosome maintenance protein 7(mcm-7), HPV-L1, and Ki-67 were analyzed using immunohistochemical methods. HPV and high-risk (HR)-HPV were detected in 14 (41.1%; 95% confidence interval (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 was expressed in 66.7% (95% CI 42.8–90.1%) of HR-HPV-positive cases and was significantly more frequent and stronger in HR-HPV-positive cases than in HPV-negative cases. There was no significant difference in the occurrence or distribution of mcm-7 or Ki-67 expression between HPV-positive and HPV-negative cases. HPV-L1 expression was not observed in any of the cases examined. HPV infection may have had an etiological role in 41% of the examined cases of penile cancer in Japan.