Images from my CT. The Dilemma of Treatment

The axial image is above, the coronal below.The coronal image shows the mass almost in the midline above the diaphragm. The axial image shows the mass in front of the spine. The little black dot beside the mass is air in my esophagus.The mass is behind the heart and liver in the axial scan. A large radiation treatment poses a risk to my heart and spinal cord.
This is the only evidence of tumor. However the consensus is that there are likely othe microscopic foci of tumor and this is apparently something seen with MCC.
So what are the options?
Surgery is ruled out by everyone. It would be a horrendous operation for me, and not likely to offer enough chance of prolonged benefit to make it worthwhile.
Radiation treatment alone is a possibility, likely to obliterate this mass and I would likely avoid serious long term side effects.
Radiation preceded by chemotherapy. This is Dr Flam's suggestion. The chemo might shrink the tumor so the field if radiation could be decreased. Also, without radiation at the same tome, the effect of the chemo could be assessed. Chemo could possibly delay or prevent new metastases.
Radiation followed by chemotherapy. Hit it first with the best shot, and use chemo to try to clean up microscopic distant disease.
The problem with chemotherapy is that it reduces the immune response to the tumor. Even killing 99% of the tumor cells won't prevent recurrence if the immune system is crippled.
Dr Nghiem proposes a new treatment which has shown promise in animals, but I don't know if it has been tried in humans. Instead of 30 radiation treatments over 6 weeks, one triple shot given once. It would injure many cells rather than kill them. The hope is that these injured cells release antigens that the immune system will recognize as "not self" and create antibodies to kill the tumor cells all over the body.
There is little to lose with this approach. If it fails, the other possibilities above are still available, and in the meantime I may have several months of good quality of life. If it succeeds, I will be a pioneer patient.