Dialog Box

About ovarian cancer

Information on ovarian cancer including types, risk factors and prevention.

What are the ovaries?

The ovaries are two small almond shaped organs that are part of the female reproductive system. Each ovary measures about 2-4 cm across and they sit on either side of the uterus. Other parts of the female reproductive system include the fallopian tubes, cervix and vagina.

Each ovary contains germ cells that eventually develop into eggs (ova). The ovaries also produce the hormones oestrogen and progesterone, which regulate your menstrual cycle and affect the development of female body characteristics – such as breasts, body hair and body .

What is ovarian cancer?

Ovarian cancer is a general term used to describe a cancerous (malignant) tumour starting in one or both ovaries. The ovaries are made up of three main kinds of cells – epithelial cells, stromal cells and germ cells. Each of these cells can develop into a different type of tumour. The average age of women when they are diagnosed with ovarian cancer is age 64. It is mainly diagnosed in women over the age of 50; however, there are cases diagnosed in younger women.

Ovarian cancer is the eighth most common cancer in Australia. About 1720 Australian women are diagnosed each year.

Types of ovarian cancer

There are several types of ovarian cancers:

  • Epithelial tumours which are the most common type (account for about 90% of ovarian cancers) and is cancer that starts in the cells lining in the surface layer (epithelial) of the ovary. There are several subtypes of epithelial ovarian cancers.
  • Germ cell tumours which begin in the cells eventually developing into eggs. This type of ovarian cancer is rare and accounts for approximately 5% of ovarian cancers.
  • Stromal cell and other rare types include sex-cord stromal cell ovarian cancer, stromal tumours and sarcomas.

All these different types of ovarian cancer behave differently and are treated differently. Within these types, there are different subtypes of tumours.

If you have been diagnosed with a rare type of ovarian cancer, it may be difficult to find specific information on your cancer. This can be upsetting and feel isolating. You may find it helpful to visit the Rare Cancers website. You may find their Knowledgebase section especially helpful. It an online collection of resources covering over 200 rare cancers, specialist hospitals with cancer centres, multi-disciplinary teams, and clinician contacts with special interests in rare cancers as well as relevant clinical trial listings.

What are the risk factors for ovarian cancer? 

We don’t know the exact causes of most ovarian cancers. However, we do know there are factors that may increase a woman’s risk of developing ovarian cancer.

Increasing Age

Getting older is the biggest risk factor for developing ovarian cancer. Ovarian cancer can happen at any age, but it is usually in women who have been through menopause, with the average age of diagnosis being age 64.

Hereditary Factors

These account for approximately 20% of ovarian cancers. Hereditary factors include:

  • inheriting a faulty gene such as a mutation in BRCA1 or BRCA2 genes
  • Women of Ashkenazi Jewish descent have a higher incidence of BRCA mutations than the general population
  • having a strong family history of ovarian, breast or some other cancers (colorectal or endometrial). 
Other Factors

Other factors that may increase the risk of ovarian cancer include:

  • having endometriosis, a previous breast cancer or diabetes
  • use of hormone replacement therapy (HRT) (this applies to some ovarian cancer types)
  • being overweight
  • smoking, which may slightly increase the risk of developing mucinous ovarian cancer
  • not having had children – women who have not had children are at a slightly higher risk.

Are there any ways you can reduce your risk?

There are ways in which you can reduce the risk of developing ovarian cancer:

  • surgical removal of the ovaries and fallopian tubes
  • having children
  • using oral contraceptives.

However, these methods are not suitable for all women, and many women having adopted protective measures may still develop ovarian cancer. It is important to discuss your risk, and appropriate management, with your doctor.

For information on dealing with cancer during COVID-19, please visit our COVID-19 page.