Can chewing the skin on the inside of your mouth and cheeks and smoking cause mouth cancer?

Yes: Any constant irritation to oral tissues can eventually cause changes to the tissue in those area which can lead to cancer. Denture patients who have constant rubbing of their dentures are very susceptible to this. Biting ones cheeks can do the same thing and anyone who smokes already has an increased risk or oral cancer.

Cancer risks: Smoking and drinking alcohol are known to be oral cancer risks. In over 40 years of dental practice I have never seen cheek biting lead to cancer. Combining risks (smoking and cheek biting) together may increase the risk. Why take a chance with your life, stop smoking before it's too late.