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Ovarian Cancer Cell Types

By Cancer Research UK

Epithelial cell types
About 9 out of 10 tumors of the ovary diagnosed (90%) are this type. Epithelial ovarian cancer means the cancer started in the surface layer covering the ovary. There are various types of epithelial cancers of the ovary

  • Serous

  • Endometrioid

  • Clear cell

  • Undifferentiated or unclassifiable

Serous epithelial ovarian cancer is the most common type, making up about two thirds of the cases diagnosed. Doctors now think that most high grade [see grading info below] serous ovarian cancers actually start in cells at the far end of the fallopian tube, rather than the surface of the ovary. These early cancer cells then spread to the ovary and grow.

About 1 in 10 epithelial ovarian cancers (10%) are undifferentiated or unclassifiable. These tumours have cells that are so very undeveloped that it is not possible to tell which type of cell the cancer started from.


Germ cell types

Around 1 or 2 out of 100 ovarian cancers (1 to 2%) are germ cell cancers. They start from the egg making cells of the ovary. As well as these, there are also non-cancerous (benign) forms of germ cell tumor, which doctors sometimes call dermoid cysts.


Ovarian teratoma
Ovarian teratoma is a type of germ cell tumor. Germ cell tumors are cancers that begin in egg cells in women or sperm cells in men. There are two main types of ovarian teratoma.


Mature teratoma - which is benign
The mature teratoma is the most common type of ovarian germ cell tumor. It is most often diagnosed in women during their reproductive years (from teens to forties). Mature teratoma is often called a dermoid cyst. It is removed with surgery and the condition is then cured.


Immature teratoma - which is cancerous
Immature teratomas are usually diagnosed in girls and young women up to their early 20s. These cancers are rare. They are called immature because the cancer cells are at a very early stage of development. Most immature teratomas of the ovary are cured, even if they are diagnosed at an advanced stage.


Stromal cell types

Granulosa tumors
Granulosa tumors are rare tumors of the ovary. They are a type of stromal tumor. The stroma is the supportive tissue of the ovary. Out of 100 women with ovarian cancer, fewer than 5 will have a granulosa tumor (5%). There are 2 main types of granulosa tumors: 1) Functioning tumors, which produce hormones, 2) Nonfunctioning tumors, which don’t produce hormones. Functioning tumors make the female hormone estrogen.


Symptoms of granulosa tumors
The symptoms of functioning tumors are usually hormone related. These symptoms include: 1) Menstrual changes (periods). If you are still having periods, they may become irregular, they may be very heavy and you may bleed between periods. 2) Vaginal bleeding. If you have had your menopause the most common symptom is vaginal bleeding. This happens because the hormones the tumor produces makes the lining of the womb thicker. This means that you may also need some tests to check your womb as well. 3) Breast tenderness. You may have breast tenderness and vaginal discharge due to the hormones. Other symptoms of granulosa tumors can include: Pain in the abdomen, swelling of the abdomen, constipation, passing urine more often than usual.



Borderline ovarian tumors

Borderline ovarian tumors are different to ovarian cancer because they do not grow into the supportive tissue of the ovary (the stroma). They are also called tumors of low malignant potential. About 10 out of 100 epithelial ovarian tumors (10%) are borderline tumors.


Borderline ovarian tumours grow slowly and most are diagnosed at an early stage, when the abnormal cells are still within the ovary. Abnormal cells can sometimes break away from the tumour and settle elsewhere in the body, usually the abdomen. These do not usually grow into the underlying tissue. They are called non-invasive implants.


Borderline ovarian tumours are treated in a different way to ovarian cancers and are usually cured with surgery alone.


Primary peritoneal carcinoma

A small number of ovarian cancers are a type called primary peritoneal carcinoma. The cancer develops from cells that form the membrane around abdominal organs. The peritoneum is a layer of thin tissue that lines the abdomen and covers all of the organs within it, such as the bowel and the liver. The peritoneum protects the organs and acts as a barrier to infection…. Primary peritoneal cancer (PPC) is a rare cancer of the peritoneum. It is very similar to the most common type of ovarian cancer called epithelial cancer [see above]. This is because the lining of the abdomen and the surface of the ovary come from the same tissue when we develop from embryos in the womb. Doctors now think that most high grade serous cancers actually start in the far end of the fallopian tube rather than the surface of the ovary or peritoneum. PPC is always either stage 3 or stage 4. This is an advanced cancer. PPC does sometimes affect the ovaries but to be a PPC it must only be on the surface of the ovary.

Soft tissue sarcomas

Soft tissue sarcomas – cancers of the supporting tissues of the body, including the muscles, nerves, fat, blood vessels and fibrous tissues – can also affect the ovary.

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