My father was diagnosed with stage iv cancer twice. He had surgery, chemo and radiation, and then it came back and he had two more surgeries. He recently had a forth surgery to remove his hardware from the second surgery.
Definitely talk to your care team. If a treatment exists, they're the ones who know about it and have the right information. My dad's doctors did not give him false hope. Sometimes they were brutally, unflinchingly honest about his chances. I think mindset is important in these situations.
They told dad after the reoccurance that immunotherapy could be an option for him, as he had had the maximum radiation he could have, but thankfully he hasn't needed it.