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What is ovarian cancer?

Ovarian cancer is when abnormal cells in the ovary begin to grow and divide in an uncontrolled way, and eventually form a growth (tumour).

If not caught early cancer cells gradually grow into the surrounding tissues and may spread to other areas of the body.

There are different types of ovarian cancer. The type depends on the type of cell the cancer started in.

Most cases of ovarian cancer are epithelial cancers. This means the cancer started in cells covering the ovary or fallopian tubes. Doctors now think that most epithelial cancers start in cells at the end of the fallopian tubes rather than the ovary.

Primary peritoneal cancer and fallopian tube cancer

Primary peritoneal cancer and fallopian tube cancer are similar to epithelial ovarian cancer and are treated in the same way. 

Primary peritoneal cancer (PPC) starts in the thin layer of tissue lining the inside of the abdomen. This tissue lining is called the peritoneum.  PPC cells are the same as the most common type of ovarian cancer cells.  

Fallopian tube cancer starts in the fallopian tubes, which link the ovaries to the womb.

The ovaries and reproductive system

The ovaries are part of a woman's reproductive system, which is made up of the:

  • vulva
  • vagina
  • womb or uterus (which includes the cervix)
  • fallopian tubes
  • ovaries

There are 2 ovaries, one on each side of the body. The ovaries produce an egg each month in women of childbearing age.

Diagram showing the parts of the female reproductive system

This video shows more detail about the female reproductive system. 

The ovaries and fertility

Women are able to have children between puberty (when the periods start) and the menopause (or change of life, when the periods stop). The age when periods start and stop varies a great deal.

In the middle of each menstrual cycle (mid way between periods), one of the ovaries releases an egg. It travels down the fallopian tube to the womb. The lining of the womb gets thicker and thicker, ready to receive a fertilised egg. If the egg is not fertilised by sperm, the thickened lining of the womb is shed as a period. Then the whole cycle begins again.

Ovarian hormones

The ovaries also produce the female sex hormones. These are:

  • oestrogen
  • progesterone

The ovaries produce these hormones throughout the years when women can become pregnant. The hormones control the menstrual cycle. As you get older and closer to menopause, the ovaries make less and less of these hormones and periods eventually stop.

Ovarian hormones also help to protect the heart and bones and maintain brain and immune system health.

The ovaries produce a small amount of the male hormone testosterone. It is not completely clear what role testosterone has in women. But doctors think it helps with muscle and bone strength. And it may have a role in a woman’s sex drive (libido).

Ovarian cysts

In young women the ovaries are about 3cm long. After the menopause they tend to shrink. Doctors can't usually feel the ovaries during a medical examination, except in young, thin women.

Some women have cysts on their ovaries. Cysts are fluid filled sacks. They are not usually cancerous.

In women of childbearing age, small cysts develop in the ovary every month as an egg develops. This is normal and they usually disappear without treatment within a few months. You should have tests if the cysts:

  • are there for longer than normal
  • are unusually large
  • cause symptoms
  • develop when you are past your menopause

Who gets ovarian cancer

Your risk of developing ovarian cancer increases as you get older. The risk is greatest in those aged between 75 and 79.

We don't know exactly what causes epithelial ovarian cancer. But some factors may increase or reduce the risk. 

Factors that increase the risk include:

  • getting older
  • inherited faulty genes
  • having breast cancer before

Factors that may reduce the risk include:

  • taking the contraceptive pill
  • having children
  • breastfeeding

How common it is

Around 7,400 women are diagnosed with ovarian cancer in the UK each year. This makes ovarian cancer the 6th most common cancer in women.

Last reviewed: 
13 Dec 2018
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    Accessed September 2020

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    Lippincott, Williams and Wilkins, 2015

  • High grade serous ovarian carcinomas originate in the fallopian tube
    S Intidhar Labidi-Galy and others
    Nature Communications, 2017. Volume 8, Issue 1093

  • Cancer and its Management (7th edition)
    J Tobias and D Hochhauser
    Wiley-Blackwell, 2015

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