Human cancers caused by human papillomavirus and human polyomaviruses : role of cytology -- Role of cytology in human cancers due to Epstein-Barr virus and Kaposi sarcoma herpes virus -- Human cancers following hepatitis B and hepatitis C virus infections : diagnostic role of cytology -- Human cancers caused by human T-cell leukemia virus type 1 and human immunodeficiency virus : role of cytology