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Types of ovarian cancer

Women discussing ovarian cancer

This page tells you about the different types of ovarian cancer. You can find the following information

 

A quick guide to what's on this page

Types of ovarian cancer

Epithelial ovarian cancer is the most common type, making up about 9 out of 10 tumours of the ovary (90%). Rarer types of ovarian cancer include germ cell tumours (cancer of the egg making cells of the ovary) and sarcomas.

Epithelial ovarian cancer generally starts in the surface layer covering the ovary. There are various subtypes of epithelial ovarian cancer. Serous epithelial ovarian cancer is the most common. Doctors now think that some serous cancers actually start in cells at the far end of the fallopian tube, then spread to the ovary. Other subtypes of epithelial ovarian cancer are mucinous, endometrioid, clear cell, undifferentiated or unclassifiable. At the moment they are all generally treated in the same way. But doctors and researchers are investigating whether the less common subtypes need to be treated in a different way to serous epithelial ovarian cancer.

Borderline ovarian tumours

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

Borderline ovarian tumours grow slowly and most are diagnosed at an early stage, when the abnormal cells are still within the ovary. They are usually cured with surgery alone.
 

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Epithelial ovarian cancer

About 9 out of 10 tumours of the ovary diagnosed (90%) are this type. So this section discusses treatment for epithelial ovarian cancer.

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
  • Mucinous
  • 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 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.

Researchers are investigating in clinical trials whether the rarer types of epithelial ovarian cancer need to be treated any differently to the serous type. But at the moment, they are generally treated in the same way. The main treatments are surgery and chemotherapy.

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. We have information about primary peritoneal cancer in the question and answer section.

 

Germ cell and other rare ovarian tumours

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 tumour, which doctors sometimes call dermoid cysts. We have information about both these types of ovarian teratoma (a type of germ cell tumour) in the question and answer section.  

Other rare types of cancer can affect the ovary, for example stromal tumours and sarcomas. This section does not cover these rarer types of ovarian cancer. Look in help and support for organisations that produce cancer information. They will be able to give you the information you need about your type of cancer.

 

Borderline ovarian tumours

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

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.

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Updated: 16 January 2014