Is A Raised, Painless Area Inside My Mouth Caused By Smoking Harmless As Doctors Say, Or Could It Be Cancer?

I have been noticing this raised area inside my mouth for the past ten days. No pain or burning. I saw an oral surgeon and a ENT surgeon. They say there is no reason to fear, it is caused by smoking. Quitting smoking will fix it. I want to know if both my doctors are right or if I really have reason to be afraid? Or is it some kind of cancer or pre-cancer? I had dental scaling done a month ago. No, I don t have a sore throat, earache or any other symptoms. And I am 34