I have had 2 dogs with bladder cancer, both females. One was a dog I took in as a foster because she got dumped at the vets office for "leaking" and had been relegated to the outdoors because her owner couldn't deal with her ...... in the house. The vet wanted to try her on PPA/DEG to see if it helped the leaking. Well, it ended up being a bladder tumor. We opted not to have the surgery done due to her age, but she responded well to piroxicam for the next 6 weeks which were probably the best 6 weeks of her life.
The other one was a rescue Collie that we adopted when she was 8. She did not have any leaking at all but was having some backend problems with walking. Once diagnosed, again, opted for not operating mainly because of the tumor location, but put her on piroxicam. It caused her stomach lining to rupure and she filled up with blood so we had to euthanize her. If I had it to do over again, I would still have given the piroxicam because of it working so well on the previous dog and it was really the only chance we had of shrinking the tumor to prolong her life.