Tumors in dogs

[Bearkiller]

Anyone have any experience with rapid growth tumors on dogs. I have a 5 year old walker that was fine friday and saturday had a growth the size of a softball and sunday morning the vet said it had double in size again. The blood supply was as big around as a pinkie. The xray showed a spot on the lungs as well although she said it could just be fluid. Likely is that its cancer as well and she said we'll know in 6 months or so since the biopsy is expensive and quite frankly will have no impact on treatment. If anyone has any experience with this, let me know. Thanks.