Certain or oncogenic viruses can cause cancer by disrupting normal cellular functions. They integrate their genetic material into the host cell's DNA, leading to mutations and uncontrolled cell growth. Human Papillomavirus (HPV) is linked to cervical and other cancers, Hepatitis B and C viruses (HBV and HCV) to liver cancer, Epstein-Barr virus (EBV) to lymphomas and nasopharyngeal carcinoma, and Human T-cell Leukemia Virus Type 1 (HTLV-1) to adult T-cell leukemia/lymphoma.

These viruses can activate oncogenes or inactivate tumor suppressor genes, facilitating tumorigenesis. For example, HPV inactivates tumor suppressor proteins p53 and Rb. Oncogenic viruses also evade the immune system, promoting chronic inflammation and creating an environment conducive to cancer.

Vaccines for viruses like HPV and HBV have reduced virus-related cancers, and research continues to develop treatments targeting these viral infections and their effects, aiming to manage better and eliminate virus-induced cancers.