Ovarian Cancer Stages and Classification

This is the seventh page in the Understanding Ovarian Cancer Guide. This guide was developed by the HealthTree Education Team and was last updated and reviewed on May 20, 2026.

Doctors use "stages" to describe how far cancer has grown and whether it has spread. Knowing the stage of your cancer helps your care team plan the best treatment and understand your prognosis.

Ovarian cancer staging is performed at the time of surgery, since exploring the abdomen is the only reliable way to determine the full extent of disease. Ovarian cancer is most commonly staged using the FIGO (International Federation of Gynecology and Obstetrics) system, which is closely aligned with the AJCC TNM system. This page focuses on the FIGO stages, which are most commonly used in clinical practice.

The FIGO Staging System

FIGO staging for ovarian, fallopian tube, and primary peritoneal cancer uses four main stages (I–IV), with subcategories within each. The larger the number, the more advanced the cancer.

Stage I — Cancer is confined to the ovaries or fallopian tubes

• Stage IA. Cancer is in one ovary or fallopian tube. The capsule (outer covering) is intact, and no cancer is found on the surface or in fluid from the abdomen.
• Stage IB. Cancer is in both ovaries or both fallopian tubes. Capsules are intact, and no cancer is found on the surface or in abdominal fluid.
• Stage IC. Cancer is in one or both ovaries or fallopian tubes, with one of the following: surgical spill of tumor (IC1), capsule rupture before surgery or cancer on the surface (IC2), or cancer cells found in fluid from the abdomen (IC3).

Stage II — Cancer has spread to other pelvic organs

• Stage IIA. Cancer has spread to or involves the uterus or the other ovary/fallopian tube.
• Stage IIB. Cancer has spread to other pelvic organs, such as the bladder or rectum.

Stage III — Cancer has spread beyond the pelvis or to lymph nodes

Stage III is the most common stage at which ovarian cancer is diagnosed. Cancer has spread beyond the pelvis to the lining of the abdomen (peritoneum) and/or to lymph nodes in the back of the abdomen (retroperitoneal lymph nodes).

• Stage IIIA. Cancer is limited to the pelvis on visual inspection, but microscopic spread is found outside the pelvis (IIIA1) or there is microscopic spread to retroperitoneal lymph nodes only (IIIA2).
• Stage IIIB. Visible cancer outside the pelvis is 2 cm or less in size, with or without spread to retroperitoneal lymph nodes.
• Stage IIIC. Visible cancer outside the pelvis is larger than 2 cm, and/or there is spread to retroperitoneal lymph nodes. Includes spread to the surface of the liver or spleen, but not into these organs themselves.

Stage IV — Cancer has spread to distant sites

• Stage IVA. Cancer cells are found in fluid around the lungs (pleural effusion).
• Stage IVB. Cancer has spread to organs outside the abdomen (such as the lungs, distant lymph nodes, or brain) or into the inside of the liver or spleen.

Tumor grade

In addition to stage, the grade of the tumor is an important factor in ovarian cancer. The grade explains how abnormal the cancer cells look under the microscope.

• Low-grade (Grade 1). Cells look more like normal cells and tend to grow more slowly.
• High-grade (Grade 2–3). Cells look very abnormal and tend to grow and spread more quickly. Most epithelial ovarian cancers are high-grade serous carcinomas.

Recurrent ovarian cancer

Ovarian cancer commonly returns after initial treatment, particularly in advanced stages. When it does, doctors often classify recurrence based on how long it has been since the last platinum-based chemotherapy:

• Platinum-sensitive recurrence. Cancer returns more than 6 months after completing platinum-based chemotherapy. These cancers tend to respond well to platinum chemotherapy again.
• Platinum-resistant recurrence. Cancer returns within 6 months of completing platinum-based chemotherapy. Treatment typically uses different drugs and may include clinical trials.
• Platinum-refractory disease. Cancer progresses during or shortly after initial platinum-based chemotherapy.
  Your care team will work with you to determine the best next steps based on the timing and location of recurrence and the treatments you have already had.