Staging is the process of finding out how widespread a cancer is. Most ovarian cancers that are not obviously widespread are staged at surgery. One of the goals of surgery for ovarian cancer is to take tissue samples fordiagnosis and staging. To stage the cancer, samples of tissues are taken from different parts of the pelvis and abdomen and examined under the microscope.

Staging is very important because ovarian cancers have different prognoses at different stages and are treated differently. The accuracy of the staging may determine whether or not a patient will be cured. If the cancer isn’t accurately staged, then cancer that has spread outside the ovary might be missed and not treated. Once the cancer has been given a stage it does not change, even when it comes back (recurs) or spreads (metastasizes) to new locations.

Ask your cancer care team to explain the staging procedure. After surgery, ask what your cancer's stage is. In this way, you will be able to make informed decisions about your treatment. One of the reasons it is important to be operated on by a gynecologic oncologist is that you are more likely to be staged accurately.

Ovarian and fallopian tube cancer is most often staged using the FIGO system. This system relies on the results of surgery to determine the extent of the primary tumor (often described by the letter T), the absence or presence of metastasis to nearby lymph nodes (described by the letter N), and the absence or presence of distant metastasis (described by the letter M). This information is combined to determine the final stage. Primary peritoneal cancer (PPC) is staged in a similar way, but there is no stage I.

The American Joint Committee on Cancer has another way to stage ovarian, fallopian tube, and primary peritoneal cancers. This also uses T, N, and M categories, however this staging is slightly different from the most recent FIGO staging.

Stages of ovarian and fallopian tube cancer

Once a patient's T, N, and M categories have been determined, this information is combined in a process called stage grouping to determine the stage, expressed in Roman numerals from stage I (the least advanced stage) to stage IV (the most advanced stage). Many stages are divided into substages designated by adding letters and sometimes additional numbers to the Roman numerals.

Stage I

The cancer is only within the ovary (or ovaries) or fallopian tube(s). It has not spread to organs and tissues in the abdomen or pelvis, lymph nodes, or to distant sites.

Stage IA (T1a, N0, M0): Cancer has developed in one ovary, and the tumor is confined to the inside of the ovary; or the cancer has developed in one fallopian tube, and is only inside the fallopian tube. There is no cancer on the outer surface of the ovary or fallopian tube. Laboratory examination of washings from the abdomen and pelvis did not find any cancer cells.

Stage IB (T1b, N0, M0): Cancer has developed in both ovaries or fallopian tubes but not on their outer surfaces. Laboratory examination of washings from the abdomen and pelvis did not find any cancer cells.

Stage IC (T1c, N0, M0): The cancer is present in one or both ovaries or fallopian tubes and any of the following are present:

• The tissue (capsule) surrounding the tumor broke during surgery, which could allow cancer cells to leak into the abdomen and pelvis (called surgical spill). This is stage IC1.
• Cancer is on the outer surface of at least one of the ovaries or fallopian tubes or the capsule (tissue surrounding the tumor) has ruptured (burst) before surgery (which could allow cancer cells to spill into the abdomen and pelvis). This is stage IC2
• Laboratory examination found cancer cells in fluid or washings from the abdomen. This is stage IC3.

Stage II

The cancer is in one or both ovaries or fallopian tubes and has spread to other organs (such as the uterus, fallopian tubes, bladder, the sigmoid colon, or the rectum) within the pelvis. It has not spread to lymph nodes or distant sites.

Stage IIA (T2a, N0, M0): Either

• Cancer that started in the ovaries has spread to or has invaded (grown into) the uterus or the fallopian tubes, or both,
• that started in the fallopian tubes has spread to the ovaries, the uterus or both.

Stage IIB (T2b, N0, M0): The cancer has grown into other nearby pelvic organs such as the bladder, the sigmoid colon, or the rectum.

Stage III

The cancer is in one or both ovaries or fallopian tubes, and one or both of the following are present:

• has spread beyond the pelvis to the lining of the abdomen
• has spread to lymph nodes in the back of the abdomen (retroperitoneal lymph nodes)

Stage IIIA1 (T1 or T2, N1, M0): Cancer is in one or both ovaries or fallopian tubes, and it may have spread or grown into nearby organs in the pelvis. Areas of cancer spread are found in retroperitoneal lymph nodes, but there are no other areas of cancer spread.

• IIIA1(i): the areas of cancer spread in the lymph nodes is 10 mm (millimeters) across or smaller
• IIIA1(ii): the areas of cancer spread in the lymph nodes is greater than 10 mm across

Stage IIIA2 (T3a2, N0 or N1, M0): Cancer is in one or both ovaries or fallopian tubes, and it may have spread or grown into nearby organs in the pelvis. During surgery, no cancer is visible to the naked eye in the abdomen (outside of the pelvis). However, when biopsies are checked under a microscope, tiny deposits of cancer are found in the lining of the upper abdomen. The cancer may also have spread to retroperitoneal lymph nodes, but it has not spread to distant sites.

Stage IIIB (T3b, N0 or N1, M0): There is cancer in one or both ovaries or fallopian tubes, and it may have spread or grown into nearby organs in the pelvis. Deposits of cancer large enough for the surgeon to see, but 2 cm (about 3/4 inch) or smaller across, are in the abdomen. These deposits may be on the outside (the capsule) of the liver or spleen. Cancer may have also spread to the lymph nodes, but it has not spread to the inside of the liver or spleen or to distant sites.

Stage IIIC (T3c, N0 or N1, M0): The cancer is in one or both ovaries or fallopian tubes, and it may have spread or grown into nearby organs in the pelvis. Deposits of cancer larger than 2 cm (about 3/4 inch) across are seen in the abdomen and these may be on the outside (the capsule) of the liver or spleen. Cancer may have also spread to the lymph nodes, but it has not spread to the inside of the liver or spleen or to distant sites.

Stage IV (any T, any N, M1)

This is the most advanced stage of ovarian cancer. In this stage the cancer has spread to the inside of the spleen, liver, lungs, or other organs located outside the peritoneal cavity. (The peritoneal cavity is the area enclosed by the peritoneum, a membrane that lines the inner abdomen and some of the pelvis and covers most of its organs.)

Stage IVA: Cancer cells are found in the fluid around the lungs (this is called a malignant pleural effusion) with no other areas of cancer spread outside the pelvis or peritoneal cavity.

Stage IVB: Cancer has spread to the inside of the spleen or liver, to lymph nodes besides the retroperitoneal lymph nodes, and/or to other organs or tissues outside the peritoneal cavity. This includes the lungs, the brain, and the skin.