When you receive an ovarian cancer diagnosis, your medical team aims to identify:
- the type and subtype of ovarian cancer
- the stage of the ovarian cancer (how much cancer there is and how far it has spread)
- the grade of the ovarian cancer (how fast it is likely to grow and spread)
An international system of staging is used, which looks at how far the ovarian cancer has spread. This involves scans, examining you during surgery and taking numerous samples (biopsies). Finding out the stage of your cancer is an important part of the diagnosis because it can influence your treatment options. This staging system is called the FIGO system, named after its authors - the International Federation of Gynaecological Oncologists (Fédération Internationale de Gynécologie et d'Obstétrique.)
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).
Metastases are lumps of cancer cells away from the primary cancer. Cells from the primary cancer can spread to other organs through the blood vessels and lymph vessels.
The FIGO and TNM staging codes for ovarian cancer are listed below. These staging codes are also used in staging fallopian tube and peritoneal cancer which are treated in a similar way to ovarian cancer.
Staging criteria for cancer of the ovary, fallopian tube, and peritoneum
Stage I (T1-N0-M0): The cancer is limited to the ovary/ovaries or fallopian tubes and has not spread.
Stage IA (T1A-N0-M0): Only one ovary (or fallopian tube) is affected by the cancer, and the tumour is confined to the inside of the affected ovary or fallopian tube. No cancer is detected on the surface of the ovary or fallopian tube and there are no malignant (cancerous) cells detected in the washing fluid from the tummy (abdomen) and pelvis.
Stage IB (T1B-N0-M0): Both ovaries (or fallopian tubes) are affected by the cancer but no cancer is detected in either the surface of the ovaries (or fallopian tubes) or in fluid taken from the tummy (abdomen) and pelvis.
Stage IC (T1C-N0-M0): The cancer is limited to one or both ovaries or fallopian tubes, with any of the following:
- Stage IC1: (T1C1-N0-M0): The ovary tissue surrounding the tumour (capsule) is no longer intact as it was ruptured during the surgery.
- Stage IC2: (T1C2-N0-M0): The ovary capsule was ruptured (burst) before surgery or there is evidence of cancer on the outer surface of at least one of the ovaries or fallopian tubes.
- Stage IC3: (T1C3-N0-M0): Cancerous cells are detected in washing fluid taken from the tummy (abdomen) or pelvis.
Stage II (T2-N0-M0): The cancer is in one or both ovaries or fallopian tubes and has spread into the pelvis (eg onto the uterus [womb] or bladder). The pelvis is the area circled by your hip bones. There is no spread of the tumour outside of the pelvis.
- Stage IIA (T2A-N0-M0): The cancer has spread into the uterus (womb) and/or fallopian tubes.
- Stage IIB (T2B-N0-M0): The cancer is affecting other organs in your pelvis (eg bladder or rectum.)
Stage III: The cancer has spread outside of the pelvis into the tummy area (abdomen) and/or the lymph nodes at the back of the abdomen (called retroperitoneal lymph nodes).
- Stage IIIA (T1/2-N1-M0 or T3A-N0/N1-M0): The cancer is in one or both ovaries or fallopian tubes. During surgery no cancer is visible outside the pelvis within the abdomen to the naked eye but tiny deposits of cancer are detected in the lining of the abdomen (peritoneum) or in the fatty apron (omentum) under a microscope. The cancer might or might not have spread to nearby lymph nodes.
- Stage IIIB (T3B-N0/N1-M0): Tumours less than 2cm in diameter are visible outside the pelvis within the abdomen and nearby lymph nodes may or may not contain cancerous cells.
- Stage IIIC (T3C-N0/N1-M0): Tumours more than 2cm in diameter are detected outside the pelvis within the abdomen and may be on the outside of the liver or spleen.
Stage IV: The cancer has spread outside of the abdomen and pelvis to more distant organs.
- Stage IVA (any T-any N-M1A): The cancer cells are found in the fluid around the lungs.
- Stage IVB (any T-any N-M1B): The cancer has spread to the inside of the spleen or liver or to distant lymph nodes or to other organs such as the lungs and bones.
Grading can help predict how the cancer will behave, including how fast it is likely to grown and spread, which may impact on the treatments recommended for you.
There are some ovarian tumours that rarely spread. These are referred to as borderline or atypically proliferative tumours (not cancers).
In the most common type of ovarian cancer the tumours are simply divided into low grade and high grade and a grading number is not given. The most common type of ovarian cancer is high grade serous carcinoma. There is a low grade serous counterpart which is less common.
All other ovarian cancers are graded as 1, 2 and 3.
Grade 1 (well differentiated) cancers have cells that closely resemble normal cells and are less likely to spread or recur (come back.)
Grade 2 (moderately differentiated) cancers and Grade 3 (poorly differentiated) cancers show increasing abnormality of appearance compared to normal cells. They are also increasingly more likely to spread and recur (come back.)
Differentiation refers to the process by which cells become specialised for their role and place in the body, so well differentiated cells are highly specialised for their role and place.
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Last reviewed: June 2018
Next Review: May 2021