Staging and grading of ovarian cancer

The stage of a cancer is a term used to describe its size and whether it has spread beyond its original area of the body. Knowing the stage of the cancer and how quickly it's likely to grow (the grade|) helps the doctors to decide on the best treatment, and it also gives a rough idea of the outlook. 

Like many cancers, ovarian cancer is grouped into four stages, Stages 1–4. For stages 1–3, there are also sub-stages, which further describe the size and extent of the cancer.

It’s often not possible to stage an ovarian cancer before a laparotomy (a type of operation) is done and the results of any biopsies are known.

Staging

We describe a commonly used staging system in this section.

Borderline tumours

Borderline tumours are made up of low-grade cells that are unlikely to spread. They are usually completely cured by surgery and rarely require further treatment.

Stage 1

Stage 1 ovarian cancer only affects the ovaries. This stage is divided into three sub-groups:

• Stage 1a The cancer is only in one ovary.
• Stage 1b The cancer is in both ovaries.
• Stage 1c The cancer is at either stage 1a or 1b, and there are cancer cells on the surface of one or both ovaries, or in the fluid taken from within the abdomen during surgery, or the ovary has burst (ruptured) before or during surgery.

Stage 2

Stage 2 ovarian cancer has begun to spread outside the ovaries to other areas within the pelvis. There are three sub-groups: 

• Stage 2a The cancer has spread to the womb or fallopian tubes.
• Stage 2b The cancer has spread to other structures within the pelvis, such as the rectum or bladder.
• Stage 2c The cancer is at either stage 2a or 2b, and there are cancer cells in the fluid taken from within the abdomen during surgery.

Stage 3

The cancer has spread beyond the pelvis to the lining of the abdomen (a fatty membrane called the omentum), and/or to abdominal organs such as the lymph nodes in the abdomen, or the upper part of the bowel.

• Stage 3a The tumours in the abdomen are very small and cannot be seen except under a microscope.
• Stage 3b The tumours in the abdomen can be seen but they are 2cm or smaller.
• Stage 3c The tumours in the abdomen are larger than 2cm or they may have spread to nearby lymph nodes.

Stage 4

The cancer has spread to other parts of the body such as the liver|, lungs| or distant lymph nodes| (for example in the neck).

Recurrent cancer

If the cancer comes back after initial treatment this is known as recurrent cancer.

Grading

The grade of a cancer gives an idea of how quickly it may develop. To find the grade of your cancer, your doctors will look at a sample of the cancer cells under the microscope. The cancer may be graded as:

• Grade 1 (low grade) – the cancer cells are growing slowly, look quite similar to normal cells (are well differentiated) and are less likely to spread than high-grade cancers.
• Grade 2 (moderate grade) – the cells look more abnormal and are growing slightly more quickly.
• Grade 3 (high grade) – the cancer cells are growing more quickly, look very abnormal (are poorly differentiated) and are more likely to spread than low-grade cancers.