Canker sores are not malignant and cannot and will not lead to mouth cancer.
Although painful canker sores have nothing to do with cancer and are caused by thing such as acidic or spicy foods, vitamin deficiencies, hormones, stress, or autoimmune disorders.
Canker sores will heal on their own within 2 to 3 weeks so any sores in your mouth that last longer than 2 to 3 weeks should be checked out by a doctor.