What to do to tell if I have mouth/oral cancer?

See specialist. The best answer is to see an ENT who will do a complete mouth/throat along with a complete ENT exam to evaluate for any signs of cancer. Typically cancerous lesions in the mouth are white or red, may bleed easily or not heal, or are slowly enlarging. In the us the risk is definitely increased in smokers, heavy alcohol drinkers, or chewing tobacco users. However there are other causes too.