The term "oral cancer" is used for any cancer that develops in tissues of the mouth (known as the oral cavity) or the throat area at the back of the mouth (known as the oropharynx).
Oral cancers are part of a group of cancers referred to by doctors as head and neck cancers; oral cancers make up about 85 percent of head and neck cancers.
Oral cancer includes cancer of the lip, tongue, salivary glands, lining of the cheeks, gums, floor of the mouth (area under the tongue), roof of the mouth (hard palate), soft palate (area at back of the roof of the mouth), uvula, and tonsils.
As many cancers grow they spread to other tissues or organs. The spreading of cancer is called metastasis. Cancer cells migrate to nearby tissues and then can reach other organs and distant parts of the body by entering blood vessels, lymph vessels or nerves. Cancer cells often appear first in nearby lymph nodes in the neck. Oral cancers can metastasize to the lungs, liver and bones where they form new tumors and risk damage to those newly invaded tissues and organs.