Laz, i too was in pretty good share, knocking down an ironman a year. My treatment devistated me. I was done about 26 montha ago and it took a good 6 months before I could run or ride well, swimming was a bit eaiser. I did lose alot of muscle so it is frustrating comming back. I am weaker than I was before, but still have the desire to work out. You got plenty of advise in the previous posts but here is one more. We all lose some of our salivia during radiation. it takes a while to come back. I bought a camelback still run and ride with it!
It is a loooong road back but just keep moving forward! You will make it back

Steve