It has long been hypothesised that oncogenic viruses such as high risk human papillomaviruses (HPV) may have causal roles in some breast and prostate cancers. However, conclusive evidence in support of this hypothesis has been elusive. In this report we demonstrate by in situ PCR and standard PCR, that Epstein- Barr virus (EBV) and high risk HPVs are present in many normal, benign and malignant breast and prostate tissues.
Materials and methodsAustralian de-identified formalin fixed or DNA extracted from fresh frozen samples were used in this study. Standard PCR sequencing and in situ PCR was carried out on the cancer and normal specimens.
• The detection of viruses was higher in fresh frozen samples than in formalin fixed samples
• The prevalence of EBV and HPV is significantly higher in breast cancer as compared with normal breast specimens. The proportion of specimens in which no viruses were identified is significantly lower in breast cancer specimens than normal breast specimens
• The prevalence of both EBV and HPV in the same specimen was significantly (three- to four-fold) higher in breast cancer specimens than normal control breast specimens (38% breast cancer compared with 10% normal breast specimens)
• The presence of HPV alone or in combination with EBV was significantly higher in prostate cancer than in benign hyperplastic and normal prostate tissues
• EBV and HPV were sometimes identified in the same nucliei of cells in breast cancer (dcis) and prostate cancer tissues by in situ PCR
• The presence of HPV associated koilocytes in breast and prostate specimens is striking
We conclude that (i) EBV and HPV gene sequences are present and co-exist in many human breast and prostate cancers, and (ii) EBV and HPV may collaborate in some breast and prostate cancers.