Thank you for the query.
Ascites means that the cancer has spread in the abdominal cavity and the liver is failing. Black stools are probably due to bleeding from upper GI tract (esophageal varices
or stomach) what indicates poor liver condition. Right leg edema is probably caused by veins thrombosis
All this conditions are life threatening and unfortunately not much can be done. Lack of appetite
is understandable. You can try Megace medicine or intravenous feeding
Hope this will help.