At least 15% 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 are eager to find out if the cancer may be hereditary.
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.
Inheriting a faulty BRCA1 or BRCA2 gene is involved in most cases of hereditary ovarian cancer.
The BRCA1 and BRCA2 genes both make a chemical substance that helps your body prevent cancer. Most men and women have two normal copies of the BRCA1 and BRCA2 gene. Some women have a genetic fault in one copy of their BRCA1 or BRCA2 genes and so they don’t produce a normal amount of this cancer-fighting substance. These women are at a higher risk of developing breast or ovarian cancer, along with some other cancers.
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 10-15% risk of developing ovarian cancer.
You inherit one copy of each of your genes from your mother and a second copy of each of your genes from your father. If one of your parents has a faulty BRCA1 or BRCA2 gene, there is a 50% chance that you may inherit their faulty copy and a 50% chance that you may inherit their normal copy. If you inherit a faulty copy, then each of your children has a 50% chance of inheriting it from you. Both men and women can pass on the BRCA gene even though men don’t have ovaries.
Another known genetic link to ovarian cancer is inheriting a syndrome called hereditary nonpolyosis colorectal cancer syndrome (HNPCC). In HNPCC, inherited faulty genes increase the risk of colorectal, ovarian, endometrial, renal tract and other gastrointestinal cancers. Women with HNPCC have about a 12% lifetime risk of developing ovarian cancer.
There are also other rare genetic links to ovarian cancer, and ongoing research may uncover genetic links that are not currently known.
Women who are most likely to have inherited a faulty gene that may increase their risk of ovarian cancer are those with a strong family history of ovarian or breast cancer.
If you are concerned about your family history of cancer and the possibility of having inherited a genetic fault, ask your doctor to refer you to a family or familial cancer clinic, located in most major public hospitals throughout Australia.
There is an online tool that you and your doctor can use together to assess your risk of developing ovarian or breast cancer, based on your family history of the diseases. Ask your doctor to assess the tool online at Cancer Australia.
Genetic testing is a big step that you will need to consider carefully. After taking a detailed family history, a genetic counsellor will talk to you about the positives and negatives of having the test done.
If you choose to have genetic testing, a sample of your blood will be taken and tested. If a faulty gene that increases your risk of ovarian cancer is found, the genetic counsellor will talk with you about offering genetic testing to other family members. To find a specialised familial cancer service near you, click here or call 1300 660 334 for more information.
Women who find out that they have an increased genetic risk of ovarian cancer should ask to be referred to a gynaecological oncologist who can advise about ways of reducing the risk of developing ovarian cancer or suggest a surveillance program, which aims to look for early signs of the cancer.