There are some kinds of tongue or oral cancer that first show up as unexplained mouth sores that won't heal. Assuming that you don't have any other risk factors (heavy tobacco and/or alcohol use, family history of oral cancer), it's very unlikely that your sores indicate cancer or will become cancer, but if they don't heal, go see your dentist to get checked out.
These are the signs of oral cancer:
-- Swellings/thickenings, lumps or bumps, rough spots/crusts/or eroded areas on the lips, gums, or other areas inside the mouth
-- The development of velvety white, red, or speckled (white and red) patches in the mouth
-- Unexplained bleeding in the mouth
-- Unexplained numbness, loss of feeling, or pain/tenderness in any area of the face, mouth, or neck
-- Persistent sores on the face, neck, or mouth that bleed easily and do not heal within two weeks
-- A soreness or feeling that something is caught in the back of the throat
-- Difficulty chewing or swallowing, speaking, or moving the jaw or tongue
-- Hoarseness, chronic sore throat, or changes in the voice
-- Ear pain
-- A change in the way your teeth or dentures fit together – a change in your "bite"
-- Dramatic weight loss
