Hello and welcoem to OCF. If you have something that has been in your mouth for years then it would be unlikely that it is cancer. Oral cancer is a fast moving cancer. The only way to know is with a biopsy that would be done by an oral surgeon or and ENT. Most dentists refer you to someone else for a biopsy. It is not unheard of for a dentist to not recognize oral cancer. Have you ever had an oral cancer screening? It should be part of your yearly checkup at the dentist. If you are concerned, make an appointment and get it checked out. Dont get upset, if it is cancer then it can be cured. The "what if" game only will drive you crazy with worry, please go about your regular life until you know for sure if you have cause to worry. Hopefully you have learned what smoking can do to you and you get rid of the cigs. Its not worth your life for a couple puffs. Best of luck.