Symptoms can vary but usually begin with a white spot or sore on the inside of the mouth. Over time it will become gradually worse and the skin may begin to deteriorate and begin to come off. Some people have to have part of their jaw removed if the cancer spreads.
Mouth cancer may appear as a lump or ulcer in the mucous membranes and is often manifested as a deep,hard crack in the tissue that is often pale (not always).
You may have sore gums or a sore that doesn't heal, a sore throat, your lining of your mouth may thicken. You could have a hard time chewing or swallowing.
Symptoms include nonhealing ulcers, bleeding in gums, hard firm mass, rapidly growing mass in mouth. History of smoking, alcohol abuse, and middle-old age are suggestive of mouth cancer.
Sores that do not go away with treatment are a symptom, also gums that bleed and do not heal. Especially when you have never had any of these before. Sores sometimes act like a fever blister.
I think the symptoms of mouth cancer could be a white spot or any kind of spot in your mouth any where, or maybe a sore that won't heal. The place will spread and the dentist or oral surgeon will need to do a bioposy on the spot.The place might not even be sore to them.