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:
- womb or uterus (which includes the cervix)
- fallopian tubes
There are 2 ovaries, one on each side of the body. The ovaries produce an egg each month in women of childbearing age.
This video shows more detail about the female reproductive system.
The female reproductive system includes a number of parts. The ovaries hold the eggs which are released each month during child bearing age. They also produce sex hormones which control periods. The fallopian tubes connect the ovaries to the womb (also called the uterus).
When an egg is released it travels down the fallopian tube towards the womb. At this time, sperm from the male can pass into the fallopian tube where it may meet the egg and fertilise it. Fertilised eggs pass down the fallopian tube to the womb, which holds and protects the baby during pregnancy. The lining of the womb is called the endometrium. It thickens during the menstrual cycle ready for pregnancy. If you don’t become pregnant you have a period which is when the lining sheds.
The cervix is the lower part of the womb. It is the opening into the vagina. During a period or menstruation blood passes from the womb through the cervix and then to the vagina. The vagina also opens and expands during sexual intercourse and stretches during childbirth to allow a baby to come out.
On the outside of the body is the vulva. It is made up of two pairs of lips. Between these is the opening of the vagina. Above the vagina is the urethra: a short tube that carries urine from the bladder to outside of the body and above the urethra is the clitoris: a very sensitive area that gives sexual pleasure.
For more information about cancers that can start in the female reproductive system, go to cruk.org/cancer-types
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.
The ovaries also produce the female sex hormones. These are:
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).
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
The risk of developing ovarian cancer increases as you get older. Most cases of epithelial ovarian cancer (the most common type) are in women older than 50.
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
How common it is
In 2015, around 7,300 women were diagnosed with ovarian cancer in the UK. This makes ovarian cancer the 6th most common cancer in women.