Certain viruses are known to be oncogenic, meaning they can cause cancer. For instance, the human papillomavirus (HPV) is associated with cervical cancer, while hepatitis B and C viruses are linked to liver cancer. Additionally, the Epstein-Barr virus (EBV) is associated with Burkitt's lymphoma and nasopharyngeal carcinoma. Understanding the link between these viruses and cancer can help in developing targeted antiviral therapies that may reduce cancer risk.