This isn't to try and sound rude, by comparing dogs to people, but to me, dogs are more important than people and it's all I have for experience but yes, it does suck
Seeing my dog, battle 2 forms of it for almost 6 months and watching him fade away before my eyes was absolutely awful. I wouldn't wish cancer on anyone, human or animal

I'm really sorry you had so many experiences with it and it's gotta be hard for you no doubt, sending big hugs to you