I want to thank the three people who posted such helpful responses to me here. I appreciate the information and encouragement. Right now, the hardest part is waiting for the results of the CAT scan and bloodwork, and not knowing how bad it is yet. In answer to my son's tobacco history, he has chewed on occasion, but not regularly at all. He has also smoked on occasion, but again, not regularly. He is a chronic asthmatic, so we have always been completely against any tobacco use for him (neither of us are smokers or chewers). He picked up on his older brother's smoking habit back in middle school, sadly. This surgeon who removed the cancer in his cheek told my son that it was not tobacco related, although I'm not sure how you really know that.
There is so much to think about right now and so much fear of the uknown. We are focusing on the hope and faith of his full recovery because we believe that faith and fear cannot live in the same place. I have to say, though, that I can do nothing but cry this morning. We have two younger children, ages 11 and 13, who still live at home with us. Once I got them off to school today, I started in on the despondent crap and am trying to buck up here.
Again, I appreciate all the input and look forward to continuing updates and corresponding. I am thrilled that you are such strong survivors!