Ovarian Cancer: Stages and Grades

Approved by the Cancer.Net Editorial Board, 04/2015

ON THIS PAGE: You will learn about how doctors describe a cancer’s growth or spread. This is called the stage. In addition, this section covers the grades which describes the difference between cancerous tissue and healthy tissue. To see other pages, use the menu on the side of your screen.

Staging is a way of describing where the 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 the cancer's stage, so staging may not be complete until all of the tests are finished. Staging is when the doctor maps out where the cancer is in your body. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient's prognosis, which is the chance of recovery. There are different stage descriptions for different types of cancer. In addition, treatment recommendations may vary even for ovarian cancer of the same stage due to other important factors.

TNM staging system

One tool that doctors use to describe the stage is the TNM system. Doctors use the results from diagnostic tests and scans to answer these questions:

  • Tumor (T): How large is the primary tumor? Where is it located?
  • Node (N): Has the tumor spread to the lymph nodes? If so, where and how many?
  • Metastasis (M): Has the cancer metastasized to other parts of the body? If so, where and how much?

The results are combined to determine the stage of cancer for each person. There are four stages: stages I through IV (one through four). The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatments.

Here are more details on each part of the TNM system for ovarian cancer:

Tumor (T)

Using the TNM system, the "T" plus a letter or number (0 to 4) is used to describe the size and location of the tumor. Some stages are also divided into smaller groups that help describe the tumor in even more detail. Specific tumor stage information is listed below.

TX: The primary tumor cannot be evaluated.

T0 (T plus zero): There is no tumor in the ovary.

T1: The tumor is limited to one or both ovaries.

T1a: The tumor is contained within one ovary. No part of the tumor has spread to the surface of the ovary, and no cancer cells are found in the abdominal fluid.

T1b: There are encapsulated (self-contained) tumors in both ovaries, but no tumor is touching an ovarian surface. No cancer cells are found in the abdominal fluid.

T1c: The tumor is in one or both ovaries, but the capsule has ruptured (burst), or the tumor has spread to the ovarian surface, or cancer cells are found in the abdominal fluid.

T2: The tumor involves one or both ovaries and has spread into the pelvis.

T2a: The tumor has grown into the uterus and/or fallopian tubes, but no cancer cells are found in the abdominal fluid.

T2b: There is cancer in other pelvic tissue, but no cancer cells are found in the abdominal fluid.

T2c: The tumor has grown into the pelvic area, such as in T2a or T2b, but cancer cells also are detected in the abdominal fluid.

T3: The tumor involves one or both ovaries and has spread microscopically (cancerous cells can be seen when tissue or fluid sample is viewed under a microscope) into the abdominal area outside the pelvis or has spread to pelvic lymph nodes.

T3a: Microscopic metastasis is in the peritoneal area (the tissue that lines the abdominal wall and covers most of the organs in the abdomen) beyond the pelvis.

T3b: Metastasis measuring 2 centimeters (cm), which is a little less than one inch, or smaller is discovered outside the pelvis.

T3c: Metastasis larger than 2 cm is in areas outside the pelvis and/or the cancer has spread to the regional nodes (pelvic or paraortic) lymph nodes.

Node (N)

The "N" in the TNM staging system stands for the lymph nodes, the tiny, bean-shaped organs that help fight infection. Lymph nodes in the pelvis are called regional nodes. Lymph nodes in other parts of the body are called distant lymph nodes.

NX: The regional lymph nodes cannot be evaluated.

N0 (N plus zero): No cancer was found in the regional lymph nodes.

N1: The cancer has spread to the regional nodes (pelvic or paraortic) lymph nodes. T3, T3a, and N1 are sometimes used interchangeably.

Metastasis (M)

The "M" in TNM system indicates whether the cancer has spread to other parts of the body, called a distant metastasis.

MX: Distant metastasis cannot be evaluated.

M0 (M plus zero): There is no cancer beyond the peritoneal area.

M1: The cancer has spread beyond the peritoneal area.

Cancer stage grouping

Doctors assign the stage of the cancer by combining the T, N, and M classifications. In addition, the FIGO system, or the Federation Internationale de Gynecologie et d'Obstetrique, is another standard system used by most doctors to stage ovarian cancer. This system uses Roman numerals.

Stage I: This stage describes cancer that is located only in the ovaries (T1, N0, M0).

Stage IA: The cancer is encapsulated and is located in only one ovary with no spread to pelvic lymph nodes or other parts of the body (T1a, N0, M0).

Stage IB: The cancer is encapsulated and is located in both ovaries with no spread to pelvic lymph nodes or other parts of the body (T1b, N0, M0).

Stage IC: The cancer is in one or both ovaries with either a ruptured capsule or tumor spread to the ovarian surface or cancerous cells in the abdominal fluid (T1c, N0, M0).

Stage II: The cancer is in one or both ovaries and has grown into the pelvis (T2, N0, M0).

Stage IIA: The cancer has grown into the uterus or fallopian tubes, but not to the pelvic lymph nodes or distant organs (T2a, N0, M0).

Stage IIB: The cancer has spread to other pelvic tissue, but not to lymph nodes or distant organs (T2b, N0, M0).

Stage IIC: The cancer has spread into the pelvic area and is shedding cancer cells into the abdominal fluid (T2c, N0, M0).

Stage III: The cancer is located in one or both ovaries and the pelvis and has spread into the peritoneum (T3, N0, M0).

Stage IIIA: The cancer has spread microscopically into the peritoneal cavity (T3, N0, M0).

Stage IIIB: The cancer has spread into the peritoneal area with areas of tumor growth that are 2 cm or smaller (T3b, N0, M0).

Stage IIIC: This stage describes any cancer that has spread into the peritoneal area with areas of tumor growth larger than 2 cm (T3c, N0, M0). Or, the cancer has spread to the lymph nodes in the retroperitoneal or inguinal areas (any T, N1, M0).

Stage IV: This stage describes any cancer that has spread to distant organs (any T, any N, M1).

FIGO Ovarian Cancer Staging

Another way to The Roman numerals are stages used in another widely used staging system from the Federation Internationale de Gynecologie et d'Obstetrique, or FIGO. The FIGO system is the standard system used by most doctors to stage ovarian cancer.

FIGO Stage I: The cancer is only in the ovaries.

FIGO IA – The cancer is limited to one ovary. No cancer found on the surface of the ovary and no cancer found in the abdominal area. (T1a, N0, M0)

FIGO IB – The cancer is limited to one ovary. Not cancer found on the surface of the ovary and no cancer found in the abdominal area. (T1b, N0, M0)

FIGO IC – The cancer is limited to one ovary. (T1c, N0, M0)

IC1 – The cancer spreading during surgery

IC2 – The cancer is found on the outside of the ovary or the ovary has burst.

IC3 – Cancer cells found in the abdominal area.

FIGO Stage II: The cancer is in one or both of the ovaries and spread below the pelvis.

FIGO IIA – The cancer has spread to the outside of the uterus or fallopian tubes. (T2a, N0, M0)

FIGO IIB – The cancer has spread to other tissues below the pelvis. (T2b, N0, M0)

FIGO Stage III: The cancer is in one or both of the ovaries and it spread outside the pelvis and surrounding lymph nodes.

FIGO IIIA – The cancer has spread to the lymph nodes behind the abdomen, with or without cancer found in the abdomen. (T3a, N0 or N1, M0)           

FIGO IIIB – The cancer has spread past the pelvis to the abdomen and is less than 2 centimeters (cm), with or without spreading to the abdominal area. (T3b, N0 or N1, M0)

FIGO IIIC – The cancer has spread past the pelvis to the abdomen and is more than 2 centimeters (cm) long, with or without spreading to the abdominal area. (T3c, N0 or N1, M0)

FIGO IV: The cancer has spread to organs beyond the ovaries except for the abdominal area.

FIGO IVa – The cancer has spread to fluid around the lungs. (any T, any N, M1)

FIGO IVb – The cancer has spread beyond the abdominal organs. (any T, any N, M1)

Recurrent cancer. Recurrent cancer is cancer that has come back after treatment. If there is a recurrence, the extent of cancer will be re-evaluated (see Diagnosis) and there may be more biopsies. Ovarian cancer re-evaluations usually include a pelvic exam, diagnostic imaging (such as CT scan, PET/CT scan, MRI, or ultrasound) and blood work (such as CA-125). Occasionally, it may include surgery, such as laparoscopy, in which a doctor inserts a thin, lighted, scope to look inside the abdominal cavity to check for recurrent disease. The goal of these procedures is to learn as much as possible about the disease’s return and to start treatment planning for recurrent disease care. See the Treatment Options section for more about the treatment of women with recurrent ovarian cancer.

Grade (G)

Doctors also describe this type of cancer by its grade (G), which 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 to predict how quickly the cancer may spread and can factor into making treatment decisions. Healthy tissue usually contains many different types of cells grouped together. If the cancer looks similar to healthy tissue and contains different cell groupings, it is called 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. The cancer’s grade may help the doctor predict how quickly the cancer will spread. In general, the lower the tumor’s grade, the better the prognosis.

However, a specific type of epithelial ovarian cancer called serous ovarian cancer is not graded this way and only considers a Low-grade and a High-grade classification, which is not necessarily the same as G1 and G2-3. They are specific histologies that also have a different biology and natural history.

GX: The grade cannot be evaluated.

GB: The tissue is considered borderline cancerous. This is commonly called low malignant potential (LMP).

G1: The tissue is well-differentiated (contains many healthy-looking cells).

G2: The tissue is moderately differentiated (more cells appear abnormal than healthy).

G3 to G4: The tissue is poorly differentiated or undifferentiated (all or most cells appear abnormal).

Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual, Seventh Edition published by Springer-Verlag New York, www.cancerstaging.net.

Information about the cancer’s stage will help the doctor recommend a specific treatment plan. The next section in this guide is Treatment Options. Or, use the menu on the side of your screen to choose another section to continue reading this guide.