Family History and the Risk for Breast or Ovarian Cancer
Overview
Many factors affect your risk (chance) of developing cancer, including age, lifestyle, environment, random changes in cells, and family history. Your risk of getting breast or ovarian cancer may be higher if someone in your family has had these cancers. If you have many relatives who have had these cancers, your risk may be even higher. For more information about risk factors for breast cancer, go to Screening for Life.
If you have a family history of these cancers, it may be important to you to find out how high your risk is. By knowing your risk, you can start screening for breast cancer at the right age, and you can decide whether to do something to lower it. For some people, this can include having surgery or taking a medicine like tamoxifen. To learn more about reducing your risk for cancer, go to Healthier Together.
Having a family history means that you have one or more biological relatives with breast or ovarian cancer. They could be:
- Relatives who have died or relatives who are still alive.
- First-degree relatives. (These are parents, sisters, brothers, and children.)
- Second-degree relatives. (These are aunts, uncles, nieces, nephews, and grandparents).
- Third-degree relatives. This includes first cousins.
Some family histories are stronger than others. Here's what determines if your family history is strong:
- How closely related you are to relatives with breast or ovarian cancer. Cancer in first-degree relatives increases your risk the most.
- How many of your relatives had or have one of these cancers. The more of these relatives there are, the stronger your family history.
- How young these relatives were when they were diagnosed.
- Having both breast and ovarian cancer in your family.
- Having a male relative who had breast cancer.
- Having an Ashkenazi Jewish heritage. These are Jewish people whose ancestors came from Eastern Europe.
Sometimes a strong family history of cancer is caused by a hereditary cancer condition. These conditions can happen when a genetic risk factor (a pathogenic variant) is passed from a parent to a child.
Some of our genes help protect the body from cancer. If one of these genes has a pathogenic variant, it might not work well. This means a person would have a higher-than-average risk of developing cancer.
Hereditary cancer is not common. About 5 to 10 out of 100 people with cancer have a pathogenic variant in a hereditary cancer gene.
Finding out about your risk
Finding out your risk for cancer can help you make important decisions about your health. Some people decide to take extra steps to prevent breast and ovarian cancer. They may have checkups and cancer screening more often, take anti-cancer medicine, or have surgery to remove the breasts, the ovaries, or both. These extra steps are not recommended for everyone with a family history of cancer. They are only for people with a high cancer risk.
The best way to find out about your risk is to talk to your doctor. You'll be asked for as much information about your family history of cancer as you can give.
Your doctor may send you to a genetic counsellor. This person is trained to help people understand their risks for certain diseases.
Genetic testing for hereditary cancer
Genetic testing can be used to find out if the cancer in your family is hereditary. In Alberta, genetic testing is covered by the Alberta Health Care Insurance Plan if your medical history or if your medical and family history show possible signs of hereditary cancer. Genetic counsellors and healthcare providers look at many factors to determine who is eligible for genetic testing.
Pathogenic variants in some genes, like BRCA1 or BRCA2, can mean you have more than a 1 in 2 chance (50%) of getting cancer. Other genes increase the risk for cancer by a smaller amount. Not everyone with a pathogenic variant in a hereditary cancer gene gets cancer.
References
Citations
- Kuchenbaecker KB, et al. (2017). Risks of breast, ovarian, and contralateral breast cancer for BRCA1 and BRCA2 mutation carriers. JAMA, 317(23): 2402–2416. DOI: 10.1001/jama.2017.7112. Accessed August 5, 2020.
Credits
Adaptation Date: 09/24/2026
Adapted By: Alberta Health Services
Adaptation Reviewed By: Alberta Health Services
Adaptation Date: 09/24/2026
Adapted By: Alberta Health Services
Adaptation Reviewed By: Alberta Health Services
Kuchenbaecker KB, et al. (2017). Risks of breast, ovarian, and contralateral breast cancer for BRCA1 and BRCA2 mutation carriers. JAMA, 317(23): 2402–2416. DOI: 10.1001/jama.2017.7112. Accessed August 5, 2020.
