Around 1 in every 2 Australians will develop cancer by the age of 80, so it’s not unusual for families to have one or more people who have had cancer. Most cancers occur by chance or are because of environmental or lifestyle exposures. It’s believed about 5% of cancers are because of genetic factors, including gene mutations. That’s why it’s important to know your family's health history. If you suspect cancer runs in your family, talking to your doctor about this is a crucial step towards understanding more about your personal risk for cancer. Here are some answers to the questions you might already have about genetic risk:
What types of gene mutations are there?
A mutation is any change in the sequence of a gene. A mutation can be harmful, beneficial or have no effect. Some mutations can increase a person’s lifetime risk of cancer. The most commonly known genes associated with hereditary breast and ovarian cancer are the BRCA1 and BRCA2 genes. Mutations in these genes can increase a women’s risk of developing breast and ovarian cancer. As science continues to evolve, so does our understanding of other genes that are associated with an increased risk of developing breast, ovarian and other cancers. A genetic mutation in these genes can be inherited from either parent – mother or father. For more information about these genes, visit our ‘Genetic Mutation Types' page.
Should I talk to my family?
Yes! It’s important to talk to your family to learn more about your family health history. Look on both your father’s side and mother’s side of the family. Document which relatives have had cancer (any type), what type of cancer, date of birth (and age at death is applicable) and how old they were when diagnosed. You can record your Family Health History on our Mapping Form. For more information on the type of family health history to collect, recording it and tips for talking to your family about health history see Pink Hope’s Kiss and Tell resources.
Does cancer run in my family?
For most women who have a family history of breast or ovarian cancer, there is usually only one person with breast or ovarian cancer. This type of family history does not automatically put the other family members at high risk for cancer as those cancers are most likely caused by ‘chance events’. Some cancers are because of changes (mutations) in combinations of unknown genes, which are still being understood by researchers.
Some cancers might be because of a mutation in a hereditary gene where genetic testing is now possible. About 5% to 15% of all cancers are because of a hereditary gene mutation. About 1 in 20 (5%) of women with breast cancer and about 1 in 7 (15%) of women with ovarian cancer have an inherited mutation in a known high-risk cancer gene.
Looking at your family history is a good starting point to assess why a history of breast and/ovarian cancer might have occurred, if genetic testing might be helpful and what this means for your risk of breast or ovarian cancer. To understand more about breast and ovarian cancer risk factors, read our Know Your Risk section.
I don’t know my family history, what should I do?
If you’re adopted or know nothing about your family history, you can talk with your GP about regular breast screening as for all women. If you have a diagnosis of breast cancer yourself but do not know your family history, you can talk with your GP, breast specialist or oncologist about whether you might be eligible for genetic testing (this may depend on your age and the exact type of your breast cancer).
If you do not have breast cancer, but you learn that an immediate relative has had breast or ovarian cancer, you can ask your GP whether you should be referred to a Family Cancer Clinic or not (this may depend on your relative’s age at diagnosis and the exact pathology of their cancer.
What types of breast or ovarian cancers are more likely to be linked to a gene mutation?
Genetic testing is offered for most types of ovarian cancer. For about 1 in 7 (15%) women, it’s linked to a genetic mutation. So, if you have ovarian cancer at any age, have a conversation with your doctor about whether you should be referred to a Family Cancer Clinic. If you have breast cancer that is ‘triple negative’ (this means where the cancer pathology report shows hormones such as oestrogen or progesterone and another protein called her-2 do not bind to the breast cells) then talk to your doctor about whether a genetic assessment is recommended.
This is usually considered if your triple-negative cancer was diagnosed before 50 or if you also have a family history of breast or ovarian cancer. There are other situations where a breast cancer diagnosis warrants more discussion with your doctor. Similarly, any man with breast cancer is also advised to discuss a genetic referral with his doctors. National referral guidelines for health professionals on when to refer to genetic services are listed here. For more on genetic testing, see here.
I have a family history of cancer. What’s next?
Once you have recorded your family health history, you can complete the iPrevent tool and/or see your GP to discuss the findings. You may also wish to submit questions to the Pink Hope Genetic Counsellor through the Ask Our Genetic Counsellor resource to assist you in researching your family health history. If relevant, your GP may refer you to a Family Cancer Clinic where you can see a Genetic Counsellor and have your risk level assessed.