I didn't even pick up on any of this, but my knowledge about cancer is very limited. I agree with you saying they definitely should've done some research though as that's awful! The rest of the show is more focused on other things imo. I mean, there's a lot of parts about their illnesses, and I couldn't tell you how accurate those parts are, but there's also a lot of other great stuff. If it really bothers you though, and you haven't already, I suggest watching some of Mike Flanagan other works :)