The cilia cannot push mucus out of the way. The airways become clogged. Tar and chemicals settle in the airways and cilia die. The smoker has to cough to get the mucus out of the lungs. Most oral cancer occurs in people who use tobacco.
Advanced cases can be fatal.
When oral cancerous tumors are removed, the skin in the mouth is usually replaced with forearm skin. This method has its drawbacks. Patients with hairy forearms have to regularly trim the hair. A more recent method uses skin from the colon. To drastically reduce your risk of oral cancer, give up tobacco.