Ovarian cancer
What is ovarian cancer?
Ovarian cancer is a malignant tumour in one or both ovaries. Recent research suggests that many ovarian cancers start in the fallopian tubes. This is different to fallopian tube cancer, which is rare.
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What causes ovarian cancer?
The causes of ovarian cancer are unknown, but the risk factors include:
- age – ovarian cancer is most common in women over 50 and in women who have stopped menstruating (have been through menopause), and the risk increases with age
- reproductive history – women who have not had children, were unable to have children, or had children over the age of 30 may be slightly more at risk
- having endometriosis – a benign (non-cancerous) condition in which the tissue that lines the uterus (endometrium) is also found in other areas of the body
- lifestyle factors – such as being overweight or eating a high-fat diet
- hormonal factors – including early puberty or late menopause, or using oestrogen-only hormone replacement therapy (HRT) for five years or more.
Some factors may reduce the risk of developing ovarian cancer. These include having children, breastfeeding, using the combined oral contraceptive pill for several years, and having your fallopian tubes tied (tubal ligation).
What types are there?
There are many types of ovarian cancer. The most common types include:
Epithelial
- starts in the surface of the ovary (epithelium)
- most common type (about 9 out of 10 cases)
- subtypes include serous, mucinous, endometrioid and clear cell cancers
Germ cell
- starts in the egg-producing cells
- rare type of ovarian cancer (about 4% of cases)
- usually develops in women under 30
Stromal cell
- rare cancer that starts in the cells that produce the female hormones oestrogen and progesterone
- can occur at any age
- may produce extra hormones, such as oestrogen
Borderline tumour
Some women (usually younger women) are diagnosed with a borderline tumour. This is not considered to be cancer because, although it can spread, it does not invade other organs. For this reason, borderline tumours are also known as low malignant potential tumours.
Who gets ovarian cancer?
Each year, about 1400 Australian women are diagnosed with ovarian cancer.
It is the ninth most common cancer in women in Australia.
Ovarian cancer is usually diagnosed in women over 50. The average age at diagnosis is 64.
The ovaries
The ovaries are part of the female reproductive system.
The female reproductive system also includes the fallopian tubes, uterus (womb), cervix (the neck of the womb) and vagina (birth canal).
The ovaries are two small, oval-shaped organs, each about 3 cm long and 1 cm thick in size. They are found in the lower part of the abdomen (the pelvic cavity). There is one ovary on each side of the uterus, close to the end of the fallopian tubes.
Each ovary is covered by a layer of cells called the epithelium. Inside the ovaries are cells called germ cells, which will eventually mature into eggs (ova).
The ovaries also release the female hormones oestrogen and progesterone from cells called stromal cells.
How ovulation works
An egg, called an ovum, is released from one of the ovaries each month (ovulation). The egg travels down the fallopian tube to the uterus. If the egg is fertilised by sperm, it can grow into a baby. If an egg is not fertilised by sperm, it disintegrates and – with the lining of the uterus – passes out of the vagina in the monthly period (menstruation).
How menopause happens
As a woman gets older, the ovaries gradually produce less of the hormones oestrogen and progesterone. The production of mature eggs also decreases and the woman’s periods become irregular and finally stop. This is known as menopause, which usually happens between the ages of 45 and 55. After menopause, it is no longer possible to conceive a child naturally.
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