Lip and oral cavity cancer is a disease in which malignant (cancer) cells form in the lips or mouth

The oral cavity includes the following:

• The front two thirds of the tongue.
• The gingiva (gums).
• The buccal mucosa (the lining of the inside of the cheeks).
• The floor (bottom) of the mouth under the tongue.
• The hard palate (the roof of the mouth).
• The retromolar trigone (the small area behind the wisdom teeth).

Most lip and oral cavity cancers start in squamous cells, the thin, flat cells that line the lips and oral cavity. These are called squamous cell carcinomas. Cancer cells may spread into deeper tissue as the cancer grows. Squamous cell carcinoma usually develops in areas of leukoplakia (white patches of cells that do not rub off).