Dont over think it. Sometimes the most simple answer is just that: it just happens. Unless the obvious like you worked in same hazardous factory handling chemicals, there is no real reason why cancer happens. It just does. Half the time, the doctors are quessing! As you can see, you lived a very health life style and it still appeared/ happened. Best thing you can do now is listen to your doctors for best course of action. Maybe get a second opinion when it comes to the radiation if suggested. Forget the surgery, the radiation is gonna kick your ass (not scare you more than you already are)! Either way, DM if you need more info or if you have any questions. We are all here to help you during this difficult time. Good Luck! You are not alone.