@nfitzs, it's understandable that you have questions about your father's treatment. Keep in mind that the current thinking is that lung cancer is not one disease, but many different diseases that share a name. What type of adenocarcinoma does your father have? Do you know which mutation: EGFR, ROS1, KRAS, ALK, . . .?

And what is the underlying lung disease that your father has? These factors in addition to his age and general health all contribute to your oncologist's choice of treatment.

I'd start by calling your oncologist, or his or her nurse, and asking them your questions as well as asking them why they are making the choice they are.

In general, immunotherapy has not been terribly effective in treating lung cancer, so there is something going on here that we're not understanding. I wish all the best for you and your dad.