Both human papillomavirus (HPV) type 18 and Epstein-Barr virus (EBV) gene sequences were identified in a high and approximately equal proportion of 100 normal, benign, and prostate cancer (PCa) specimens.

Noel J. Whitaker, MD, and colleagues noted in a report in The Prostate that although the apparently ubiquitous presence of these viruses in all three types of tissues suggests that the viruses could be harmless, HPV type 18 in particular has high oncogenic potential and may be associated with some PCa cases. HPV-associated koilocytes were identified in 24% of the PCa specimens studied.