FULLNESS IN STOMACH WITHOUT EATING ANYTHING

MY DAD HAD SURVIVED GASTRIC CANCER BUT LAST MONTH DOCTOR SAID IT HAS REOCCURRED BECAUSE IT WAS FULL OF DARK THINGS BUT BIOPSY TAKEN SHOWS NO SIGN OF MALIGNANCY . NOW THE ONLY PROBLEM IS DIET, HE IS UNABLE TO HAVE ANYTHING. LAST MONTH HE WAS DIAGONISED WITH ASCITAL FLUID WHICH DOCTOR REMOVED THROUGH NEEDLE . NOW I AM CONFUSED ABOUT REOCCURRENE IF IIT IS HOW TO TREAT THAT AND IF NOT HOW BE SAFE FROM REOCCURRENCE.HOPING FOR GOOD ANSWERS FROM MY FRIENDS.