My heart goes out to the caretakers, especially those who have to deal with cancer cachexia. I'm finding that a lot of cancer patients and families are not fully educated on how cancer changes someone's metabolism. In advanced cancer, because of the physiological changes that solid mass tumors cause, there is no evidence to suggest that aggressive nutrition support - i.e. tube feedings and IV nutrition improve morbidity (how sick someone is) or mortality (how long they might live)- in fact in some cases aggressive therapy may shorten someone's time. I think that it is important that caregivers of advanced cancer patients understand that the way in which the body uses nourishment is not something we have learned to control and if we can't change it - it would be better to let that stress go. I have seen families at each others' throats because their loved one can't eat and the caregivers think that this must mean that he/she has given up, he/she hasn't given up... the cancer is supressing the appetite and using what he/she does it for fuel... the cancer, in the advanced state, gets 'first dibs' on food.
My advice is to focus on alleviating any suffering and connecting emotionally with your loved ones and eliminating needless worries. Sorry for rambling, but I think this is an area where burdens need to be lifted.