Oncoviruses are viruses that can cause cancer. One of the most common and familiar oncoviruses is human papillomavirus (HPV), which causes six types of cancer. Hepatitis B and C are also common oncoviruses; aside from the symptoms and complications they cause on their own, they can cause liver cancer. Other oncoviruses include Epstein-Barr (linked to Burkitt lymphoma, immunoblastic lymphoma, nasopharyngeal cancer, and stomach (gastric) cancer), HIV (which can cause Kaposi sarcoma, aggressive B-cell non-Hodgkin lymphoma, and cervical cancer), human T-lymphotropic virus-1 (HTLV-1, which causes leukemia/lymphoma), human herpesvirus 8 (HHV-8, which causes Kaposi sarcoma), and Merkel cell polyomavirus, which causes Merkel cell carcinoma.
