Hi @khameroff, There is an ongoing discussion that started last Spring regarding radiation to the lung. The discussion has morphed into some other topics, but the early responses may be helpful: https://connect.mayoclinic.org/discussion/radiation-treatment-on-lul/
Generally, surgery is not done on stage IV patients (but not always). Cancer cells have already escaped the primary tumor. Treatment of the whole body is usually more beneficial. Is your lung tumor growing?

Nothing definitive. After the brain surgery, I'm still doing physical therapy for different parts of my body that aren't working like they used to, including the thoracic region of my back, right shoulder, and right hip. (The cyst was on the left side of my brain.) Two different therapists have speculated that the radiation has a stiffening effect on soft tissue, including the fascia.

I had severely low iron levels that required transfusions. No known cause. I'm still struggling with low blood sodium, and for a while, I had high blood potassium at the same time. My Oncologist says the medical community is becoming more aware of the potential long-term negative effects of radiation, especially when it's administered to the chest. I know my Onc. is regularly testing my thyroid level because of the radiation.

On the other hand, cancer has some pretty negative side effects as well! My father-in-law's lung cancer was successfully eliminated by radiation alone.