I don't have anything life threatening or scary like breast cancer, I do have a slowly crippling neuropathy, which is definitively untreatable and painful.
I also have spent a lot of time with my son, who has a congenital hip dyplasia, at a world class children's hospital. My son is able to not only walk, but run, because of what doctors, in particular one spectacular pediatric orthopedic surgeon, can do. We are surrounded there each time we go by children with far more serious issues than his, and his was not simple. He was born without a hip socket, but it is as nothing compared to what many children suffer. What the doctors are able to do for these children is amazing, but some of them will still die, and many of them will never be able to live independently.
The question is not always "why me?" but "why not me?"
Just learn to live with it is really not always a bad answer. I think there is a lot of wisdom in that advice, even if the doctors themselves don't understand the power of it.