Looks like the cancer started in his bladder. The vet consulted with an oncologist, and they have selected the right anti-inflammatory to increase comfort. We'll head to the vet at 3pm tomorrow to do a quick rectal exam and obtain the meds. The bathroom behavior (attempting to poop when he doesn't have to go) might be fixed by the meds... might not... really depends what he's feeling, and he's a Golden Retriever, so he's not prone to showing his discomfort. Now its a waiting game. There wont be much else to say about it, until he declines significantly and needs to be put down.