Gum cancer, also known as oral cancer, is an uncommon but serious type of cancer that can spread to other parts of the body. It is most often caused by exposure to certain viruses, such as the human papillomavirus (HPV), or by excessive smoking or drinking alcohol. Other risk factors include poor oral hygiene, a weakened immune system, and certain types of chewing tobacco. The disease can spread through direct contact with an infected person or through saliva, blood, or other bodily fluids. Treatment depends on the stage and type of cancer, and can include chemotherapy, radiation therapy, and surgery.