Scientists have confirmed that at least fifty percent of current cancers are closely related to viral infections, the most common cancers such as liver cancer, cervical cancer, leukemia, and nasopharyngeal cancer. There is a correlation between liver cancer and chronic hepatitis B virus infection. Ninety percent of liver cancers are hepatitis B surface antigen positive. After the hepatitis B virus infects the human body, if the hepatitis B virus is not removed, the hepatitis B virus will integrate into the human liver cell genes to develop liver cancer. There is a correlation between cervical cancer and human papilloma virus infection, leukemia and human T-lymphocyte virus infection, nasopharyngeal cancer and EBV infection, and many other cancers and viral infections. As science advances cancer will eventually be overcome, but prevention and treatment of chronic viral infections is the best way to combat cancer.