Familial ovarian cancer

Why does ovarian cancer occur?

Cell growth is controlled by a cell’s genes. Genes contain the information that determines how our cells grow and work throughout our lifetime. This information can be passed from one generation to the next (inherited).

Sometimes, genes in ovarian cells develop a change. This can cause the cells to grow out of control, leading to cancer. These genetic changes, which occur throughout life are not inherited. They occur more often in older people. Why this happens is not fully understood.

What's the risk and risk factors?

The risk of getting cancers increases with age. One in 108 women will get ovarian cancer during their lifetime.

There are many factors that influence a person's risk of getting ovarian cancer. The 2 biggest risk factors are being a woman and getting older. Most women who get ovarian cancer are over the age of 50. A family history of ovarian or breast cancer is also an important risk factor.

Family history of ovarian cancer

A family history of ovarian cancer means having 1 or more blood relatives who've had ovarian cancer. 

Some women will have a family history of cancer by chance alone but a small number may have inherited a changed gene, which increases the risk of cancer. The women most likely to have inherited a changed gene are those with the strongest family history of ovarian cancer.

Understanding your family history of ovarian cancer can help identify your risk:

  • most women have close to the average chance for the Australian population
  • some women have a moderately increased chance
  • a small number of women have a high chance

How does family history affect your ovarian cancer risk?

A woman could have a high chance of getting ovarian cancer if she has:

  1. Three or more close blood relatives on 2 sides of the family (mother’s or father’s) with breast or ovarian cancer OR
  2. Two or more close blood relatives on 1 side of the family, plus 1 or more of the following features on the same side of the family:
    • breast and ovarian cancer in the same person
    • ovarian cancer before the age of 50
    • Jewish ancestry OR
  3. Three or more close relatives on the same side of the family with bowel cancer or uterine cancer OR
  4. A family member who has had a genetic test that has shown an inherited change in a gene associated with breast or ovarian cancer

Inheriting an ovarian cancer gene

Ovarian cancer caused by inheriting a changed gene is called hereditary cancer. We all inherit a set of genes from each of our parents. Sometimes there's a change in one copy of a gene which stops that gene working properly. This is also called a mutation.

There are several genes for which inherited changes may be involved in the development of both ovarian and breast cancer. These are genes which normally prevent a woman getting ovarian or breast cancer. Some of these are genes that you may have heard of, called BRCA1 and BRCA2. Their names come from the abbreviation of 'breast cancer 1' and 'breast cancer 2'. If a woman has inherited a change in one of these genes, she has a high chance of ovarian or breast cancer. It does not mean she is certain to get cancer.

Less than 5% of all ovarian and breast cancers can be explained by an inherited gene change in BRCA1 or BRCA2.

What can you do?

The earlier a cancer is found the more successful treatment is likely to be. We recommend that women concerned about their family history talk to their doctors. It may be appropriate for some women with a strong family history to be referred to a Family Cancer Centre. Here, their risk of getting ovarian cancer or breast cancer, based on their family history, can be worked out and talked about in more detail.

For more information call our Cancer Helpline on 13 11 20. If you're worried about your risk of ovarian cancer based on your family history contact your doctor or nearest Family Cancer Centre.

for