Jeff,
In your profession, you are exposed to so many things, that the possibilities are nearly endless as far as respiratory problems, I suppose.
Have you had a positive biopsy yet?
Of course, there are so many types of cancer, as well. Some are far less ominous than others. Severe fibrosis can look a lot like cancer as well, but be relatively benign. I went through a period with my late wife, when they suspected cancer, but it was merely fibrosis and collapsed lung tissue.
I'd like to tell you not to be scared until you know all the facts, but then again, I'd be scared to death in your situation. Your profession, though, takes so much courage, that I'm sure you're facing this pretty well.
Among the things from Buddhism that I've adopted into my personal belief set is that smoke carries one's prayers to heaven. One would think, then, that the prayers of firemen would reach the heavens first and foremost.
I do believe that someone or something in heaven pays special attention to firefighters, and their prayers.
All my best to you, Jeff,
-Tom Myro