@redpowerranger , It's unfortunate that you are facing this again, but good that you had 13 years between incidents. It sounds like you are in doing well other than the cancer. Treatment decisions can be so difficult, and it's never a one-size-fits-all answer. It sounds like a frank discussion with your oncologist is in order.
What are the treatment side effects that you may face? Are there lighter alternatives to the treatment that's been proposed that may extend your life, but not necessarily cure you, allowing for a better quality of life with the time you have remaining? If you choose no treatment, what does that process look like, and what can you expect?
Remember that this is ultimately your decision. It's your body. You likely have people in your life that care for you very much. Do you think your family/friends can support your decision?