Welcome back to OCF, John. There is a small percentage of OC patients who have no known cause. From what I see among the OC patients here, I think less than 10% of all diagnosed have no known cause. This could be contributed to all kinds of things including as you mentioned mouth trauma. Unfortunately the recent increase in tongue cancers (base of tongue) among younger patients is due to the HPV virus. Sadly medical research is very expensive and OC is not one of the major cancers that gets the majority of funding. We can only hope thru the efforts of OCF spreading awareness along with funding research, and many determined individuals one day more will be known.