Other types of ovarian cancer

There are few uncommon types of ovarian cancer. Find out what they are.

Epithelial ovarian cancer is the most common type of ovarian cancer. The other types of ovarian cancer are:

• primary peritoneal cancer
• germ cell cancers
• rare ovarian tumours
• borderline ovarian tumours

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.

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.

There are also non cancerous (benign) forms of germ cell tumour, which doctors sometimes call dermoid cysts or mature teratoma.

Other rare types of cancer can affect the ovary, for example stromal tumours and sarcomas.

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 (10%) of epithelial ovarian tumours 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. 

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