Hi Paul, I was in a similar position to you back in 2009. I had a very aggressive recurrence with 6 tumors bilaterally in my neck and around my left jaw. I was originally told that it was inoperable and that I was not a candidate for further radiation as I'd already had maximum grays in a treating a previous recurrence. I was initially told that the only treatment option open to me was chemotherapy, which might slow the cancer but not get rid of it. After much discussion amongst many experts my surgeon agreed to surgically remove as much of the macroscopic deposits as was safe, and then I would have a 3 week hospital stay, receiving Cisplatin weekly and having IMRT twice daily. We did not have cyberknife in Australia and I don't think it would have been an option for me anyway given the wide area that needed treatment. I had to sign lengthy disclaimers in relation to the risks involved with having the 2nd round of radiation TX and these risks were death (carotid rupturing short term and increased risk of blockage long term), quadraplegia, nerve damage and many, many more. I was an otherwise healthy 51 year old at the time and I remember telling my RO that if it bought even another 6 months then it was worth any side effect that might come my way. Strangely the biggest side effect that I actually got I don't recall being discussed with me and that was completely losing all function of my saliva glands and my ability to eat. MY epiglottis doesn't function efficiently and I have very stiff muscles in my throat and neck, so I have a permanent PEG. I also have problems with my speech. Even with these side effects there is not a day that goes by that I regret having had this surgery and treatment. Nearly 3 years later I am still here and for that I am grateful and was very lucky. Any time I had a whine about pain or other side effects my RO used to remind me that I was very lucky to be alive. After the fact he told me that even with treatment they had my odds at less than 10%. Without TX they were 0%. I'm so very glad I lucked out and they were prepared to be very aggressive with my TX.
I know your decision can't be easy given you have other health problems, but I don't think that you would be offered the TX if there wasn't a chance that it would be effective. I hope I haven't scared you too much - nothing about this cancer is easy - but despite everything I have a good quality of life and I make the most of everyday!