We explain the different ovarian cancer stages and grades.
When you receive an ovarian cancer diagnosis, the medical team aims to identify:
- the type and subtype of ovarian cancer
- the stage of the ovarian cancer (how far it has spread)
- the grade of the ovarian cancer (how it is likely to behave)
An international system of staging is used, which looks at how the ovarian cancer has spread. This involves taking numerous samples and examining you during surgery. It is an important part of the diagnosis because it can influence your treatment options. This staging system is called the FIGO system, after its authors - the International Federation of Gynaecological Oncologists.
Another staging system used is called TNM which takes into account the size of the tumour (T), whether the cancer has spread to the lymph glands/lymph nodes (N), and whether the tumour has spread anywhere else in the body (M – for metastases).
For ovarian cancer, the TNM staging system has not been formally published yet but you may see reference to it in your pathology report so the TNM coding is included for each FIGO stage below.
FIGO staging criteria for cancer of the ovary, fallopian tube, and peritoneum
Stage I (T1-N0-M0): The tumour is limited to the ovaries or fallopian tubes.
Stage IA (T1a-N0-M0): Only one ovary or fallopian tube is affected by the tumour, and the ovary is intact. No cancer is detected on the surface of the ovary or fallopian tube and there are no malignant (cancerous) cells detected in fluid taken from the abdomen.
Stage IB (T1b-N0-M0): Both ovaries (or fallopian tubes) are affected by the tumour, but both ovaries are intact. No cancer is detected in either the surface of the ovaries or fallopian tube, or in the fluid from the abdomen.
Stage IC: The tumour is limited to one or both ovaries or fallopian tubes, with any of the following:
- Stage IC1: (T1C1-N0-M0: The ovary capsule is ruptured (no longer intact) as a result of the surgery.
- Stage IC2: (T1C2-N0-M0): The ovary capsule ruptured before surgery, or there is a detectable tumour on the ovary or fallopian tube surface.
- Stage IC3: (T1C3-N0-M0: Cancerous cells are detected in the fluid taken from the abdomen.
Stage II (T2-N0-M0): The tumour is in one or both ovaries, or fallopian tubes, and has extended into the pelvis or the peritoneum (thin flexible sheet of transparent tissue that covers the organs inside your abdomen).
- Stage IIA (T2a-N0-M0): The cancer is also affecting the uterus and/or fallopian tubes
- Stage IIB (T2b-N0-M0): The cancer is affecting other organs in your pelvis
Stage III (T1/T2-N1-M0): The tumour is in one or both ovaries, or fallopian tubes, or the peritoneum, and has also extended to the lining of the pelvis and abdomen and/or nearby lymph nodes.
- Stage IIIA1 (T1/2-N1-M0): Very tiny cancer cells are detected in the lymph nodes in the lining of the abdomen. (Stage IIIA1(i) the tumour is up to 10 mm in dimension, and Stage IIIA1(ii) the tumour is more than 10 mm in greatest dimension).
- Stage IIIA2 (T3a2-N0/N1-M0): Very tiny cancer cells are detected above the pelvis, with or without the tumour detectable in the lymph nodes in the lining of the abdomen.
- Stage IIIB (T3b-N0/N1-M0): Small tumours (less than 2cm in diameter) are detectable beyond the pelvis, and the lymph nodes may or may not contain cancerous cells.
- Stage IIIC (T3c-N0/N1-M0): Small tumours (more than 2cm in diameter) are detected beyond the pelvis, including into the non-functional part of the liver and spleen and/or there is cancer.
Stage IV – A and B (any T–any N–M1): The cancer cells have spread to another organ such as the liver, the brain or the lungs.
Grading can help predict how the cancer will behave, including how likely it is to spread, which may impact on treatments and follow up.
It is split into four categories:
Borderline or low malignant potential
This means that spread is very unlikely.
Grade 1 - Low grade tumours
Often described as 'well differentiated'. This means the cells look very similar to normal cells, and are not as likely as high grade tumours to spread.
'Moderately differentiated' tumours are in between low and high grade.
Grade 3 - High grade tumours
Described as 'poorly differentiated'. These have a tendency to grow and spread more quickly than low grade tumours.
Grade 4 - undifferentiated or anaplastic tumours.
Sometimes clinicians will refer to low and high grade ovarian cancer which is explained earlier in this section but are not the same as the grading talked about on this page.
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Last reviewed: May 2016
Next Review: June 2018