I don't have the same kind of cancer so this may be of absolutely no use to you and your husband... but may be something you could talk over with your doctor. I have colon cancer, that has spread to my lungs. One of the tumours has grown to the point it is partially blocking my bronchial airwaves. Same thing, it is not operable where it is located, but does it ever make it miserable for breathing.
What we have done a couple of weeks ago is had the tumor radiated. The plan is, I have to go through some more nastiness with the breathing/coughing while the inflammation dies down, but the radiation will hopefully shrink the tumour so it is no longer blocking the airwave. This will take a few weeks after the last radiation treatment so I can't tell you yet if it is going to be successful... but perhaps you can ask your husband's doctor if radiating the tumor is an option in your husband's case?
I'm certainly no doctor, and don't pretend to be one, so don't take this as advice on what to do... just something that you can bring up with the doctor and he will be able to tell you why it can't work in your husband's case, or if it's worth a try.
Cheryl in Vancouver