Role of HPV and Epstein–Barr virus in the development of epithelial breast tumors

Breast cancer is the leading cause of oncological morbidity in women worldwide, but its causes are still being investigated. The researchers hypothesized a possible association between breast cancer and viral infection. Some studies support this assumption, while others point out their inconclusiveness. The aim of the review was to study the association of human papillomavirus (HPV) and Epstein–Barr (EBV) infection in breast tumors. We analyzed the results of more than 100 publications demonstrating the relation between HPV and EBV infections and breast tumors of different origin. Data on the presence of viral particles were obtained by various methods: IHC, real-time PCR, and in situ hybridization, where formalin-fixed tissues were studied. We detected HPV and EBV DNA and studied the expression of HPV oncoproteins (E6, L1) and EBV latent antigens (EBNA-1, EBNA-2, EBNA-3, LMP-1). The analysis of more than 4,000 cases of benign and malignant breast tumors indicates a wide range of HPV and EBV prevalence in breast tissue (up to 86% and 56%, respectively). Despite the revealed relations between the presence of viral particles in tissues and the subsequent tumor development, the etiological role of HPV and EBV in the occurrence and progression of breast tumors remains debatable. Keywords: breast tumor, breast cancer, human papillomavirus (HPV), Epstein–Barr virus (EBV), oncoviruses