Ovarian, Fallopian Tube, and Peritoneal Cancer: Stages and Grades

Approved by the Cancer.Net Editorial Board, 10/2022

ON THIS PAGE: You will learn how doctors describe a cancer’s growth or spread. This is called the stage. Use the menu to see other pages.


What is cancer staging?

Staging is a way of describing where a cancer is located, if or where it has spread, and whether it is affecting other parts of the body.

Doctors use diagnostic tests to find out a cancer's stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor recommend the best kind of treatment, and it can help predict a patient's prognosis, which is the chance of recovery. There are different stage descriptions for different types of cancer.

For ovarian/fallopian tube cancer, the staging system developed by the International Federation of Obstetrics and Gynecology (Federation Internationale de Gynecologie et d'Obstetrique, or FIGO) is used.

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FIGO stages for ovarian, fallopian tube, and peritoneal cancer

The stage provides a common way of describing the cancer, enabling doctors to work together to plan the best treatments. Doctors assign the stage of cancer using the FIGO system.

Stage I: The cancer is only in the ovaries or fallopian tubes.

  • Stage IA: The cancer is only inside 1 ovary or fallopian tube. No cancer is found on the ovarian or fallopian tube surface or in the abdomen.

  • Stage IB: The cancer is in both ovaries or fallopian tubes. No cancer is found on the surface of the ovary or fallopian tube or in the peritoneal fluid or washings.

  • Stage IC:The cancer is in 1 or both ovaries or fallopian tubes, with any of the following:

    • Stage IC1: The tumor ruptures while it is being removed surgically, called intraoperative surgical spill.

    • Stage IC2: The tumor wall is ruptured before surgery, or there is cancer on the surface of the ovary or fallopian tube.

    • Stage IC3: Cancer cells are found in fluid buildup in the abdominal cavity, called ascites, or in the samples of fluid from the peritoneal cavity taken during surgery.

Stage II: The cancer involves 1 or both of the ovaries or fallopian tubes and has spread below the pelvis, or it is peritoneal cancer.

  • Stage IIA: The cancer has spread to the uterus and/or fallopian tubes and/or the ovaries.

  • Stage IIB: The cancer has spread to other tissues within the pelvis.

Stage III: The cancer involves 1 or both of the ovaries or fallopian tubes, or it is peritoneal cancer. It has spread to the peritoneum outside the pelvis and/or to lymph nodes in the retroperitoneum (lymph nodes along the major blood vessels, such as the aorta) behind the abdomen.

  • Stage IIIA1:The cancer has spread to the retroperitoneal lymph nodes, which are found at the back of the abdomen, but not to the peritoneal surfaces.

    • Stage IIIA1(i): Metastases, or areas of spread, are 10 millimeters (mm) or smaller.

    • Stage IIIA1(ii): Metastases are larger than 10 mm.

  • Stage IIIA2: The cancer has spread microscopically from the pelvis to the abdomen. Cancer may or may not have spread to lymph nodes in the back of the abdomen.

  • Stage IIIB: The cancer has visibly spread past the pelvis to the abdomen and is 2 centimeters (cm) or smaller, with or without spread to the retroperitoneal lymph nodes. A centimeter is roughly equal to the width of a standard pen or pencil.

  • Stage IIIC: The cancer has visibly spread past the pelvis to the abdomen and is larger than 2 cm, with or without spread to the retroperitoneal lymph nodes.

Stage IV: The cancer has spread to organs outside of the abdominal area.

  • Stage IVA: The cancer has spread to fluid around the lungs.

  • Stage IVB: The cancer has spread to the liver or spleen or to organs beyond the abdomen, including lymph nodes in the groin outside of the abdominal cavity.

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Doctors also describe ovarian/fallopian tube cancers by their grade. The grade describes how much cancer cells look like healthy cells when viewed under a microscope.

The doctor compares the cancerous tissue with healthy tissue. This helps the doctor predict how quickly the cancer may spread and may help the health care team make recommendations about the treatment plan. Healthy tissue usually contains many different types of cells grouped together. If the cancer looks similar to healthy tissue and has different cell groupings, it is called “well differentiated” or a “low-grade tumor.” If the cancerous tissue looks very different from healthy tissue, it is called “poorly differentiated” or a “high-grade tumor.” In general, the lower the tumor’s grade, the better the prognosis.

Some tumors are called borderline tumors, which are tumors of low malignant potential (LMP). They are very different from high-grade cancers and represent about 10% to 15% of epithelial ovarian/fallopian tube neoplasms, which are abnormal growths of cells. Borderline tumors typically occur in younger patients and are often confined to an ovary but can involve both ovaries. Most are serous tumors and can be associated with the presence of a tumor in the peritoneum, which can be benign or invasive.

Most epithelial ovarian/fallopian tube cancers are the serous type, and they are graded as low-grade serous carcinoma (LGSC) or high-grade serous carcinoma (HGSC). These tumors have different genetic alterations and biology.

Other types of ovarian/fallopian tube cancer, such as endometrioid cancers, may be given these grades:

  • Grade 1: The tissue is well differentiated. This means the cells look and are organized within the tumor like normal cells. These tumors tend to grow slowly.

  • Grade 2: The tissue is moderately differentiated. It shares features between well and poorly differentiated. Grade 2 is not commonly used.

  • Grade 3: The tissue is poorly differentiated or undifferentiated. All or most cells appear very abnormal and do not have any normal tissue structure. These tumors tend to grow fast and can spread rapidly.

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Information about the cancer’s stage and grade will help the doctor recommend a specific treatment plan. The next section in this guide is Types of Treatment. Use the menu to choose a different section to read in this guide.