My friend hasn't eaten in almost a month

So I have a friend of mine who has been diagnosed with some kind of spinal disorder where she only gets half the fluids her body needs, three or four tumors (which could also mean losing her arm), and type two cancer. She said that she won't make it passed 25 years of age. While this sucks for the most part, I'm concerned about how she's been doing. She seems sad at sometimes, but happy whenever I have a casual chat with her. SHe told me that she hasn't eaten in 19 days. This day it's 21. I told her to eat something, but she ended up coughing food back out. I don't know what else I could tell her. I don't want her to starve, but then she tells me she feels fine. She has also already accepted the fact that she could die. She even signed papers that tell the doctors to not resucitate her if anything happens. In fact she expects herself to die. But I don't. I think she'll pull through. I just can't get her to think that she has a chance at survival. Because I believe she does. There's many people like her who has survived cancer. Seems possible she can too. I'm not sure what to do at this point. I came here wondering if anybody had anything to say. Anything I can do, I'd like to try. Thanks.