To go off of what Bigboy said, yes, there are dogs that can detect cancer in urine (among other things). But they are TRAINED to do so. I have a Cocker spaniel with an amazing nose, and we've done nosework activities together where he'll find and alert to a specific scent. He didn't come programmed to alert to any scent, especially not something that isn't food. But with training, he can. Just like those dogs.

He goes to the bathroom with me as well. It's really less of a cancer alert and more of an attachment and the fact that he just wants to be with me.