Oral cancer, also known as mouth cancer, is a cancer of the lining of the lips, mouth, or upper throat.[6] In the mouth, it most commonly starts as a painless white patch, that thickens, develops red patches, an ulcer, and continues to grow. When on the lips, it commonly looks like a persistent crusting ulcer that does not heal, and slowly grows.[7] Other symptoms may include difficult or painful swallowing, new lumps or bumps in the neck, a swelling in the mouth, or a feeling of numbness in the mouth or lips.[8]

Reference
Wiki: Tongue cancer