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

Approved by the Cancer.Net Editorial Board, 08/2016

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

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 to decide what kind of treatment is best. Knowing the stage can help predict a patient's prognosis, which is the chance of recovery. There are different stage descriptions for different types of cancer.

Cancer stage grouping for ovarian, fallopian tube, and peritoneal cancer

The stage of ovarian, fallopian tube, and peritoneal cancer is determined by the FIGO (International Federation of Obstetrics and Gynecology) staging system. There is a TNM (tumor-node-metastasis) system that correlates with the FIGO system, and this system is applied to the pathology report after a surgery.

FIGO cancer staging for ovarian, fallopian tube, and peritoneal cancer

It is important for the doctor to find out the histologic type of the cancer, and the presumptive site of origin (where the cancer began) — whether it appears to arise from the ovary, fallopian tube or peritoneum, or if it cannot be clearly determined.

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

IA – The cancer is only inside one ovary or fallopian tube. No cancer is found on the ovarian or fallopian tube surface, or in the abdomen.

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.

IC – The cancer is in one or both ovaries or fallopian tubes, with any of the following:

IC1 – Intraoperative surgical spill

IC2 – The tumor wall is ruptured before surgery or there is cancer on the surface of the ovary or fallopian tube

IC3 – Cancer cells found in ascites (peritoneal fluid) or in the washings of the peritoneum.

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

IIA – The cancer has spread to the uterus and/or fallopian tubes and/or the ovaries.

IIB – The cancer has spread to other tissues within the pelvis.

Stage III: The cancer involves one or both of the ovaries or fallopian tubes, or 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.

IIIA – The cancer has spread to the retroperitoneal lymph nodes without spread to the peritoneal surfaces.

IIIA(i) –  Metastases are 10 millimeters (mm) or smaller

IIIA(ii) – Metastases are larger than 10 mm

IIIA2 – The cancer has spread microscopically from the pelvis to the abdomen, with or without lymph nodes with cancer in the back of the abdomen.

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.

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.

IVA – The cancer has spread to fluid around the lungs.  

IVB – The cancer has spread to organs beyond the abdomen, including lymph nodes in the groin and outside of the abdominal cavity.

Recurrent: Recurrent cancer is cancer that has come back after treatment. If the cancer does return, there will be another round of tests to learn about the extent of the recurrence. These tests and scans are often similar to those done at the time of the original diagnosis.

Grade of the cancer

Doctors also describe this type of cancer by its grade, 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 predict how quickly the cancer may spread and can be a factor in making treatment plan 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.

Some tumors are borderline cancerous, and these are called tumors of low malignant potential (LMP).

Most epithelial ovarian cancers are the serous type, and they are they graded as:

LGSC -- low-grade serous carcinoma

HGSC -- high-grade serous carcinoma

Other histologic types, such as endometrioid cancers, may be graded as follows:

Grade 1: The tissue is well-differentiated (contains many healthy-looking cells).

Grade 2: The tissue is moderately differentiated (more cells appear abnormal than healthy).

Grade 3: The tissue is poorly differentiated (all or most cells appear abnormal).

Information about the cancer’s stage will help the doctor recommend a specific treatment plan. The next section in this guide is Treatment Options. You may use the menu to choose a different section to continue reading in this guide.