What is ovarian cancer?

2013 Newcastle BT Prof. Edmondson small

The term ovarian cancer is often used as though there is just one disease - cancer of the ovaries. However there are in fact many different types of ovarian cancer. This page explains what ovarian cancer is, and gives the main types of the disease.


What is cancer?

Our bodies are made up of millions of building blocks called cells.  In order to repair damage (for example cuts and grazes) and to maintain good health, our body is constantly removing worn out cells and replacing them with new ones.  When an old cell is destroyed, one of the remaining cells will make a copy of itself by dividing into two, replacing the old cell.  This process is usually carefully controlled so that the number of new cells created is the same as the number that were removed.  However, sometimes a cell may lose the ability to respond to the signals that tell it to stop dividing. The cell will then divide uncontrollably, making more and more copies of itself, eventually forming a lump called a tumour.

What are the ovaries?

The ovaries are two small organs about the size of large olives.  They are located low in the tummy, just above the pubic area.  The ovaries are part of a woman's reproductive system.  They store a woman's supply of eggs, and each month an egg is released from one of the ovaries into the womb ready for fertilisation.  The ovaries are also responsible for making the female hormones oestrogen and progesterone.

Are all ovarian tumours cancerous?

Most tumours on the ovaries are not cancerous, but benign.  They are not life threatening and can occur for a number of reasons.  Only around 1 in 5 ovarian masses found in women still having their periods (menstruating) are cancerous. That figure rises in post menopausal women - those who have gone through the 'change' some time ago.  For women in this group it is likely that 1 in every 2 tumours will be malignant (cancerous).

Ovarian cancer

Ovarian cancer is cancer arising from the cells in and around the ovary.  In fact there are several different types of ovarian cancer, classified by the types of cells and tissue they originate from.  Increasingly research is beginning to show that in future, treatment regimes will be more closely targeted according to the type and subtype of ovarian cancer.

If you have been diagnosed with ovarian cancer it can be useful for you to understand about the type of ovarian cancer you have, its subtype, the extent to which it has spread (the stage) and the potential aggressiveness of the cancer (the grade). Some women do not wish to know so much detail. It is a personal choice but can aid discussions about treatment options and future management, including potential access to clinical trials.

Types of ovarian cancer

  • Epithelial ovarian cancer

This is by far the most common type of ovarian cancer and occurs in around 9 out of every 10 cases. The cancer arises from the cells that line or cover the ovaries (the epithelium). There are several different subtypes which can behave and respond differently to treatment.

  • Borderline tumours

Borderline tumours as their name suggests are of low malignancy potential. This means they are very slow growing and have not yet begun to spread or damage the tissue around them. They are usually treatable by surgery alone.

  • Germ cell tumours

About 5% of ovarian cancers are germ cell tumours - that is around  1 in 20 cases.  The cancer arises in the cells that are destined to form eggs within the ovaries, and so tend to be found in younger women. There are a number of different subtypes of germ cell tumour, which means each subtype is quite rare, and it is important that treatment takes place at a centre with expertise in dealing with this particular type of ovarian cancer. When treated by experts, they are normally curable.

  • Sex cord stromal cell tumours

Sex cord stromal cell tumours account for less than 5% of ovarian cancer cases. They arise from the connective cells that hold the ovaries together and produce the female hormones.

  • Other rarer types of tumour

These types of ovarian cancer are very rare. We will in due course supply more detailed information, but for present they include:

  • Choriocarcinoma
  • Dysgerminoma
  • Endodermal sinus tumours
  • Embryonal carcinoma
  • Granulosa cell tumours
  • Primary peritoneal ovarian cancer (in the lining of the peritoneum - which means even women who have had their ovaries removed can develop this type of ovarian cancer, however it is very uncommon)
  • Sarcomas
  • Sertoli-Leydig tumours
  • Teratoma, immature, mature or mixed


Last reviewed: February 2013

Next Review: February 2014