BB, Sorry to hear about your nephew, it's really hard to take in, as a patient, and especially for the family, as I had found out when I got older.
Beating cancer has a lot to do with the mind, and staying positive, which isn't as easy as it sounds. I would say medicine makes up about 20%, and the doctor about 5%, the rest is all on the patient.
I was a stage 4 plus non hodgekins lymphomem, when I was 16, they gave me 6 months. I am the first survivor in Northern CA for that cancer type, at my age level. I am now 48. I had to receive an experimental protocol, with no real chance of success (at that time), it turns out they were right, because now they use 1/3 less of the medicine, and the protocol is 9 mts, instead 18 mts.
My family helped to keep me positive, and I wanted to graduate from high school for my mom, I think a part of that is the reason I beat the cancer. I didn't realize until my 30's how much my family went through, and I am truly grateful now, for everything they did, just to keep my spirits up.
Best thing for you to do and help your nephew, is just to be there for him, and keep him positive, during his hard journey, cancer is beatable, much more than 20+ years ago.
Good luck, and he'll be in my prayers, smoke up!