Staging and grading of ovarian cancer

When ovarian cancer is diagnosed, it is important to know the stage and grade of the cancer. The stage of a cancer describes the size of the tumour and whether it has spread to other parts of the body.

Grading is about how the cancer cells look under the microscope compared with normal cells. The grade of a cancer describes how quickly it is growing.

Doctors usually use the FIGO staging system to describe the stage of ovarian cancer. It describes ovarian cancer in four stages. This system gives information about how far the cancer has grown and whether it has spread into nearby lymph nodes or organs.

Knowing the stage and grade of the ovarian cancer helps with decisions about treatment.

Staging

The stage of a cancer describes its size, position and if it has spread from where it started. Knowing the stage helps your doctors advise you on the best treatment for you.

Your doctor will not usually be able tell the exact stage of the cancer until after it has been removed with surgery. If an operation isn’t appropriate, they use the results of your tests to decide on the stage of the cancer.

Doctors usually stage ovarian cancer using the FIGO staging system. It divides ovarian cancers into four number stages that are also subdivided.

When reading this information, it may help to look at the diagrams showing the lymph nodes and organs near the ovaries.


Stage 1

This is early ovarian cancer.

Stage 1a – The cancer is only in one ovary.

Stage 1b – The cancer is in both ovaries.

Stage 1c – The cancer is in one or both ovaries with any of the following:

  • The tissue surrounding the ovary (capsule) has broken during surgery, which could have let cancer cells leak into the abdomen or pelvis.
  • There are cancer cells on the surface of one or both ovaries or the tissue surrounding the ovary (capsule) has broken before surgery, which could have let cancer cells leak into the abdomen or pelvis.
  • There are cancer cells in the fluid taken from the abdomen during surgery.

Stage 2

The cancer has spread outside the ovary or ovaries to other areas inside the pelvis.

Stage 2a – The cancer has spread to the womb and/or fallopian tubes.

Stage 2b – The cancer has spread to other structures within the pelvis, such as the bowel or bladder.


Stage 3

The cancer may have spread outside the pelvis to the peritoneum and/or to the lymph nodes at the back of the tummy (retroperitoneal lymph nodes). 

Stage 3a1 – The cancer has spread but only to the retroperitoneal lymph nodes.

Stage 3a2 – The cancer has spread outside the pelvis but doctors can only see this under a microscope. The cancer may have spread to the retroperitoneal lymph nodes.

Stage 3b – The cancer has spread outside the pelvis but the tumour is less than 2cm in size. It may have spread to the retroperitoneal lymph nodes. There may be cancer cells on the surface of the liver and spleen but not inside these organs.

Stage 3c – The same as stage 3b but the tumour is 2cm or larger.


Stage 4

The cancer has spread to organs outside the abdomen.

Stage 4a – The cancer has caused a build up of fluid in the lining of the lungs (called the pleura). This is called a pleural effusion.

Stage 4b – The cancer has spread to the inside of the liver or spleen, to lymph nodes in the groin or outside the abdomen and/or to other organs, such as the lungs.


Grading

Grading is about how the cancer cells look under the microscope compared with normal cells. Knowing the grade helps your doctor decide whether you need further treatment after surgery.

This is how ovarian cancers are graded:

  • Borderline tumours are made up of abnormal cells rather than cancer cells. We have more information about borderline tumours.
  • Low-grade or well-differentiated (grade 1) – The cancer cells look similar to normal cells and usually grow slowly and are less likely to spread.
  • Moderate- or intermediate-grade (grade 2) – The cancer cells look more abnormal and are slightly faster-growing.
  • High-grade or poorly-differentiated (grade 3) – The cancer cells look very different from normal cells and may grow more quickly.

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