Cancer that began in tissue covering the ovary and has spread from one or both ovaries to other parts of the abdomen. Stage III is divided into stages IIIA, IIIB, and IIIC. In stage IIIA, the tumor is found in the pelvis only, but cancer cells have spread to the surface of the peritoneum (tissue that lines the abdominal wall and covers most of the organs in the abdomen). In stage IIIB, cancer has spread to the peritoneum and is 2 centimeters or smaller in diameter. In stage IIIC, cancer has spread to the peritoneum and is larger than 2 centimeters in diameter and/or has spread to lymph nodes in the abdomen. Cancer that has spread to the surface of the liver is stage III disease.