I may be wrong but the immunotherapy (eg. Keytruda) will follow after completion of the chemotherapy (however there are evidently many different permutations as to how these treatments are given).
In my situation I also had a 5.3 cm tumor that was removed by surgical removal of the right lower lobe. My tumor was EGFR positive so the treatment regimen was cisplatin and pemextred as the chemotherapy then followed daily by oral treatment with Tagrisso. Chemotherapy will usually involve cisplatin, carboplatin or some other platinum based drug given by IV infusion over 3-4 months. Chemotherapy can be a challenge……it can take a toll on a person but everyone is different as to how they respond. The oncologists are well acquainted with all the possible side effects and how they can be managed. Take notes and ask lots of questions!

Hi @sharwi85, I'm sorry that you and your husband are dealing with this, but I'm glad that you found Mayo Connect. There are many or us here with lung cancer, living generally good lives. There is hope!
I'm glad that you'll be seeing oncology soon. It's nice to have a plan, and to move forward. 5.3cm is significant. Did your husband have a PET scan? Do you happen to know if his tumor was sent for biomarker testing?, if not you may want to ask the oncologist.