Up to 20% of epithelial ovarian cancers are thought to be the result of inheriting a faulty gene from either your mother’s or father’s side of the family.

Many women who have ovarian cancer or who have a relative with ovarian cancer want to find out if the cancer may be hereditary. Click through below to find more information about:

  • What are genes?
  • Ovarian cancer in the family
  • Inheriting an ovarian cancer gene
  • Genetic testing

Genes are small pieces of DNA, the material that acts as a master blue print for all the cells in your body. Your genes determine such things as what colour hair and eyes you have and how tall you are. Your genes also provide the recipe for building all the chemical substances in your body and keep it running smoothly. Sometimes there is an error in one of your genes that means the gene cannot do its job properly. This is called a genetic ‘fault’ or ‘defect’. In some cases, these faults can lead to disease.

Most women diagnosed with ovarian cancer do not have a history of ovarian cancer in their family. However, some women’s family history of ovarian cancer can increase their risk of developing the disease. You may have a family history by chance or because you have inherited a faulty gene that will increase your risk. Your family history of ovarian cancer may be strong if:

  • You have two or more close relatives on the same side of the family (father’s or mother’s relatives) who have had cancer.
  • The family members have all had ovarian cancer or different
  • cancers (e.g. bowel or breast) that can be caused by the same faulty gene.
  • The cancers are diagnosed when the relatives are younger
  • than age 50.
  • You have a family member who has had genetic testing confirming they have a faulty gene.
  • You have Ashkenazi Jewish ancestors (who have a higher incidence of BRCA mutations than the general population).
  • Your own cancer was diagnosed at an early age, or you have had more than one type of cancer.

Ovarian cancer caused by inheriting a faulty gene is called ‘hereditary cancer’. Having a personal or family history of ovarian, breast, colon or endometrial cancer may mean you have inherited an increased risk of developing ovarian cancer.

Generally, the more relatives from the same side of the family who have had these related cancers, the greater your risk of having a hereditary cancer. However, it is still possible to inherit a faulty gene without having a family history of these cancers.

Inheriting a faulty BRCA1 or BRCA2 gene is involved in most cases of hereditary ovarian cancer. These gene faults are named for their connection to breast cancer (BReast Cancer genes 1 and 2) but are also associated with inherited ovarian cancer as well as fallopian tube, prostate, peritoneal, pancreatic and male breast cancer.

These genes normally help to prevent cancer, but when a woman inherits a damaged version of either gene, she is less protected against cancer. Women who inherit a faulty BRCA1 gene have approximately a 40% lifetime risk of developing ovarian cancer, while women who inherit a faulty BRCA2 gene have approximately a 18% lifetime risk of developing ovarian cancer up to the age of 70.

Many women who have a faulty BRCA1 or BRCA2 gene do not have a known family history of ovarian or breast cancer. This can happen for many reasons:

  • Other family members may have inherited a faulty gene but not have developed ovarian or breast cancer.
  • There may be few females in a family, making it difficult to see a pattern of family history.
  • A new gene fault may develop.

Other known genetic factors increasing your risk of developing ovarian cancer are inheriting:

  • hereditary nonpolyposis colorectal cancer syndrome (HNPCC) (also known as Lynch syndrome)
  • RAD51C and RAD51D faulty genes (very rare).

There are also other rare genetic links to ovarian cancer, and ongoing research may uncover genetic links not currently known. Inheriting one of these gene faults increases a person’s risk of developing ovarian cancer but doesn’t mean that they will definitely develop ovarian cancer.

All women diagnosed with invasive epithelial ovarian cancer as well as those with fallopian tube or primary peritoneal cancer, regardless of their age or family history, should be offered genetic testing. They may have a BRCA1 and/or BRCA2 mutation even if they don’t have any family history. It is also recommended women who have had a previous diagnosis of invasive epithelial ovarian cancer be offered genetic testing at their next follow-up appointment with their specialist.

It is important to have a discussion with your doctor about genetic testing as there may be other reasons for you to be tested for gene mutations.

If you choose to have genetic testing, a sample of your blood will be taken and tested. If you find out you have inherited a gene fault that has caused your ovarian cancer, you can talk to your specialist cancer doctor (gynaecological oncologist) about how this may change your treatment and follow-up care. Importantly, your gene status may enable you to enter certain clinical trials. There are new drugs called ‘PARP (poly ADPribose polymerase) inhibitors’ that may be offered to women who have BRCA gene faults.

If a faulty gene associated with a higher risk of ovarian cancer is found, the genetic counsellor will suggest offering genetic testing to other family members. If other family members have inherited a faulty gene associated with an increased risk of ovarian cancer, a gynaecological oncologist can advise about ways to reduce their risk.

More Information

Cancer Council Australia has a section on family cancers with many useful resources and links (www.cancer.org.au)

Watch our webinar on Family history and genetic testing