My mom has genetic breast cancer (her 2nd bout of breast cancer, but 1st round was unrelated to the genetic kind.)
It was only in her breast and her lymph nodes were ok, although one still needed to be removed due to the location of the cancer, so in general she seems to be better off than Neckys mom. Although iirc, my mom was at least stage 2. From my understanding of it all, Necks mom would be at least stage 3, but I'm no doc.
Anyways, because of ma's history with breast cancer coupled with her testing positive for the specific gene she has, she was on a very aggressive treatment plan. Same one outlined in the GFM, I believe, so it's not outside the realm of possibility.
I will say, though - my mom may not have the beetus, fibro or COPD, but she had 2 surgeries in quick succession (to remove cancer and begin masectomies) and then almost immediately started treatment. She handled it quite well - her skin was like 4th degree burns though. She hasn't started chemo yet, but from what she tells me, radiation is worse. She drove herself everyday 1hr there and 1hr back because they live in the boons. They manage on his income along with her disability, and I believe he has insurance for her. My stepdad is a total fucking dolt with money (and in general) and also drives nearly 2 hrs daily for work, so expenses are up there.
I have yet to be asked for monetary help or to *have her be taken care of. I assure you, they have no savings.
I know we can't totally compare, but the situations are extremely similar and I thought it might give some perspective.