Grading and staging of ovarian cancer
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 - these are made up of abnormal cells rather than cancer cells.
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.
Borderline tumours are made up of abnormal cells, but they aren’t true cancers. They are sometimes called tumours of low malignant potential (malignant means cancerous). This is because they can sometimes turn into cancers, but most don’t.
Borderline tumours usually grow slowly and are unlikely to spread. They’re staged in the same way as ovarian cancers (see below). Most women who have a borderline tumour are diagnosed with early-stage disease (stage 1). Occasionally abnormal cells from borderline tumours spread and begin to grow somewhere else in the body, such as on the lining of the abdomen (peritoneum). These new growths are called ‘non-invasive implants’. They don’t usually cause problems and often don’t need to be treated. Instead the doctor may monitor them at regular check-ups.
Ovacome has a fact sheet with more information about borderline tumours.
The stage of a cancer is a term used to describe its size and whether it’s spread beyond its original area of the body. It’s often not possible to tell exactly what the stage of an ovarian cancer is until an operation has been done to remove it.
This is a commonly used staging system, called the FIGO staging system. It divides ovarian cancers into four stages:
The cancer only affects the ovaries. Stage 1 can be subdivided into:
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 and either there are cancer cells on the surface of one or both ovaries OR there are cancer cells in the fluid taken from the abdomen during surgery OR the ovary has burst (ruptured) before or during surgery.
The cancer has spread outside the ovaries to other areas within the pelvis. Stage 2 can be subdivided into:
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.
The cancer has spread beyond the pelvis to the omentum and/or to organs in the abdomen, such as the lymph nodes in the abdomen or the upper part of the bowel. Stage 3 can be subdivided into:
Stage 3a The tumours in the abdomen are very small and can only be seen under a microscope.
Stage 3b The tumours in the abdomen can be seen but they’re 2cm or smaller.
Stage 3c The tumours in the abdomen are larger than 2cm OR they may have spread to nearby lymph nodes OR they have spread to nearby lymph nodes.
The cancer has spread to other parts of the body, such as the liver, lungs or distant lymph nodes (for example in the neck).
Stage 1 is called early ovarian cancer. Stages 2–4 are called advanced ovarian cancer.
Often the stage of the cancer can only be confirmed after surgery. If the cancer comes back after initial treatment, this is known as recurrent cancer.