Oral cancer lesions are most often found on the sides of the tongue, the top of the throat at the back of the mouth (oropharynx), and the floor of the mouth. Lesions can appear red, white, or mixed. Red and mixed lesions are more likely to be cancerous. If you have a change in your mouth that lasts for more than three weeks, see your doctor or dentist. Other symptoms include a change in voice, jaw swelling, trouble chewing or swallowing, or bleeding, pain, or numbness in and around the mouth.