**Yes, they can. **
Smoking, being exposed to toxic chemicals or radiation, and carrying mutations in certain genes are some of the best-known risk factors for cancer. But another cause of cancer isn't discussed as often: viruses.
There are at least seven viruses that are known to contribute to the development of cancer in humans, either directly or indirectly. These include human papillomaviruses (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV), Epstein-Barr virus (EBV), Kaposi's sarcoma-associated herpesvirus, human T-cell lymphotropic virus and Merkel cell polyomavirus. In addition, human immunodeficiency virus (HIV) raises the risk of cancer in part by opening the door for cancer-driving viruses to invade the body.