Cancer remains in the abdomen after surgery and at least one of the following is true: (1) cancer has spread to lymph nodes in the abdomen or pelvis (the part of the body between the hips); (2) cancer has spread to or through the surface of the peritoneum (the layer of tissue that lines the abdominal cavity and covers most organs in the abdomen); (3) a biopsy of the tumor was done during surgery to remove it; (4) the tumor was removed in more than one piece.