Cancer occurs when cells in the body, in this case tongue cells, divide without control or order. Normally, cells divide in a regulated manner. If cells keep dividing uncontrollably when new cells are not needed, a mass of tissue forms, called a growth or tumor. The term cancer refers to malignant tumors, which can invade nearby tissues and can spread to other parts of the body. A benign tumor usually does not invade or spread. Tongue cancer
Tongue cancer is often grouped with other mouth cancers, such as cancer of the lips, hard palate, cheek lining, the portion of the mouth underneath the front of the tongue, or gums. These cancers are collectively known as oral cavity cancer.source: http://www.med.nyu.edu.