Sheldon, grade 3 tells only a small piece of the puzzle, it says that the cells have aggressive traits. What kind of cancer and where is it? Any lymph node involvement? Spread? Is this a new diagnosis or has she been fighting a long time? Is she not eating because of the cancer or is she scared (causing her to lose her appetite)? And if the cancer is local, fatigue is not likely to be a side effect...but is she having treatment? Chemo and radiation can sure wipe a person out and interfere with her sleep and appetite.
My breast cancer was grade III, and that was 5 years ago, today I am disease-free.
Feel free to tell us more, not much we can offer in terms of answers with this information.