Very exciting result, but not all that surprising. It has been known for a long time (although curiously ignored by oncologists) that patients who eat less have a better average survival that those who eat a lot. Doctors look at a patient's weight and implore them to eat more (like all those pro-marijuana advocates who say one of the medical benefits is increased appetite). In reality, eating less appears to be a healthier choice. This study kind of sheds some light onto why that is the case.
I think with the appetite thing there's probably some kind of co-morbidity associated with fasting + cancer. My (Completely uneducated, I know about the heart, not cancer) initial thought would be some kind of chemo interaction, lipid profiles in the blood and such.