Sorry to hear of your continued troubles. There are many other risk factors other than Smoking, Alcohol, HPV for SCHNC, although these are major ones, we often don't think about any others. Even with the best diagnosis, treatment, it's difficult for doctors to give a definite answer for chances of survival since each of us are different, and so is cancer, treatment, and include other factors, and maybe even our genes, family history, diet, which is being looked into more. Probably the biggest prognostic factor for survival is tumor size, locoregional lymph node involvement, especially having more than one node involved, so control of these is key to survival since most oral, pharyngeal failures occur locoregiionslly. It's also possible that the tonsil was the primary to begin with, and missed? Anyway, the good thing is your cancer was found early initially, and and 2nd was dealt with accordingly, and did the best you could do. Good luck with the MRI