Reviewed by: Prof Michael Quinn, Director of Oncology/Dysplasia, Royal Women's Hospital
On this page: The ovaries | Ovarian cancer | Epithelial ovarian cancer | Germ cell and sex-cord stromal cell ovarian cancers | Borderline tumours | How common is ovarian cancer? | Causes of ovarian cancer
Taken from 
Ovarian cancer booklet (2MB)
The ovariesThe ovaries are part of the female reproductive system. They contain the eggs (ova), which can make a new human life when fertilised. In women of childbearing age, a mature egg is released from one of the ovaries each month (ovulation) and travels down the fallopian tubes to the uterus (womb).
The ovaries are oval-shaped organs, each about 3cm long and 1cm thick. They're found inside the pelvic cavity, one on each side of the uterus, and are very close to the end of the fallopian tubes.
Each ovary is covered by a layer of cells called epithelium. Inside are germ cells which eventually mature into eggs. The eggs travel to the outside of the ovary to be released into the fallopian tubes. If the egg is not fertilised by sperm, it passes out of the uterus with the monthly period (menstruation).
The ovaries also contain cells that release the hormones oestrogen and progesterone. These cells are called ‘sex-cord stromal' cells.
As women get older, the ovaries gradually produce less oestrogen and progesterone. At the same time the production of eggs also decreases and a woman's periods become irregular and eventually stop. This is known as menopause, or the ‘change of life'. It usually happens between the ages of 45 and 55. After menopause it's no longer possible to have a child.
Ovarian cancer is a malignant tumour in one or both ovaries. There are 4 main types of ovarian cancer, named after the part of the ovary that's affected. Knowing exactly which type of cancer you have helps your doctor advise you on which treatment is best.
This type of ovarian cancer arises in the epithelium: the cells covering the ovary. It's the most common type of ovarian cancer. Eight out of ten ovarian cancers are epithelial.
These 2 types of ovarian cancer are very uncommon. The germ cell cancers arise in the cells that mature into eggs, and usually only affect women under 30 years of age.
Sex-cord stromal cell cancers arise in the cells which release the female hormones. These cancers can occur at any age.
Germ cell and sex-cord stromal cell ovarian cancers usually respond very well to cancer treatment and are often curable. If these cancers only affect one ovary, it may still be possible for younger women to have children after treatment.
Borderline tumours are a group of epithelial tumours that aren't as aggressive as other forms of ovarian cancer. Sometimes the words ‘low malignant potential' are used to describe borderline tumours.
The prognosis for women with borderline tumours is generally very good, whether the disease is diagnosed early or late.
In Victoria about 400 women are diagnosed with ovarian cancer each year. About 90% of ovarian cancers occur in women over the age of 40. Like most cancers, the risk of ovarian cancer increases with age.
The causes of most ovarian cancers aren't known but some factors seem to put women at a higher risk:
Many women with ovarian cancer do not have these risk factors. It's also worth noting that many women who do have the risk factors do not develop ovarian cancer.
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