Ovarian cancer is staged at surgery. Staging is based on classifications devised by FIGO [International Federation of Gynecology and Obstetrics - www.figo.org]. The stage of ovarian cancer at diagnosis is also the most important indicator of prognosis [prediction of duration, course and outcome of the disease].

Stage I - Cancer is limited to one or both ovaries.

IA	Cancer is limited to one ovary and the tumor is confined to the inside of the ovary. [There is no cancer on the outer surface of the ovary.] There is no ascites present containing malignant cells. The surface of the tumor is unruptured.
IB	Cancer is limited to both ovaries without any tumor on their outer surfaces. There is no ascites present containing malignant cells. The surface of the tumor is unruptured.
IC	The tumor is classified as either Stage 1A or 1B and one or more of the following are present: (1) tumor is present on the outer surface of one or both ovaries; (2) at least one of the tumors has ruptured; and (3) there is ascites present or abdominal [peritoneal] washings containing malignant cells.

Stage II - The tumor involves one or both ovaries with extension to other pelvic structures.

IIA	The cancer has extended to and/or involves the uterus or the fallopian tubes or both.
IIB	The cancer has extended to the bladder or rectum.
IIC	The tumor is classified as either Stage IIA or IIB and one or more of the following are present: (1) tumor is present on the outer surface of one or both ovaries; (2) at least one of the tumors has ruptured; and (3) there is ascites containing malignant cells or with abdominal [peritoneal] washings containing malignant cells.

Stage III - The tumor involves one or both ovaries, and one or both of the following are present: (1) the cancer has spread beyond the pelvis to the lining of the abdomen; and (2) the cancer has spread to the lymph nodes. The tumor is limited to the true pelvis but with histologically-proven malignant extension to the small bowel or omentum.

IIIA	During the staging operation, the practitioner can see cancer involving one or both of the ovaries, but no cancer is grossly visible in the abdomen and it has not spread to the lymph nodes. However, when biopsies are checked under a microscope, very small deposits of cancer are found in the abdominal [peritoneal] surfaces.
IIIB	The tumor is in one or both ovaries, and deposits of cancer are present in the abdomen that are large enough for the surgeon to see but not exceeding 2 cm in diameter. The cancer has not spread to the lymph nodes.
IIIC	The tumor is in one or both ovaries, and one or both of the following is present: (1) the cancer has spread to lymph nodes; (2) the deposits of cancer exceed 2 cm in diameter and are found in the abdomen.

Stage IV - Growth of the cancer involves one or both ovaries and distant metastases to the liver or lungs have occurred. Finding ovarian cancer cells in the excess fluid accumulated around the lungs [pleural fluid] is also evidence of stage IV disease.