@timpopandglamfee: I see you are new to Mayo Clinic Connect so please accept my welcome even though it's under the difficult circumstances you describe.

First of all, congratulations to you on beating cancer; as one who is going through immunotherapy myself for a form of cancer, I understand how involved that alone is. And now you are facing a very alarming and confusing situation with your husband.

There are times when the primary source of cancer cannot be determined as explained in this overview from Mayo: https://www.mayoclinic.org/diseases-conditions/carcinoma-unknown-primary/symptoms-causes/syc-20370683

It's hard searching for answers at a time like this especially when your questions have not been met with responses that are clearly definitive. It can be challenging to understand medical terminology, procedures and decisions particularly during emotional times. Most hospitals have case management teams and/or social workers who may be able to act as liaisons to assist with communication. They would be in an ideal position to assist with the individual particulars of your husband's case.

Can you ask what resources the oncology team or hospital staff has for you so you can get these details better explained to you?