I completely understand your situation. After all was said and done with our Yukon, we were a hurting unit in the wallet, which, will take a long time to pay off.
First thing I would ask is what type of X-ray are they doing? The traditional x-rays showed nothing on our boy, it was the 3D x-ray that gave us results. It's just my opinion, but with the nose I wouldn't bother with traditional x-ray. There's just so much it has to go through.
Second, you could try for a medical type credit card or checked if the vet will do a payment plan.
Yes, it could be cancer. But, it might not be, and could very well be something treatable. I always like to think there's always hope.
Hindsight would tell us to get pet insurance, to ease the financial burden just a little bit, but you can't even imagine something so horrible even happening. Only you can make the final decision, and no matter what it won't be easy.
I hope for the best.