@bryan18603, it is not uncommon for stage 4 cancer to be controlled (treated) with chemotherapy and/or other systemic therapies long term. My father was offered this for stage 4 colorectal cancer. It was explained to him that he had control over when to stop or that he could take chemo "vacations".

It is good news that the tumor and lymph nodes have responded well to treatment and have shrunk. How are the side effects of chemo/immunotherapy? Have you thought of talking about temporarily pausing treatment to have a break? Is this advisable in your situation? Might be worth talking to your oncologist about your options.