Family History and the Risk for Breast or Ovarian Cancer

Topic Overview

The average woman has a small chance of getting breast cancer and an even smaller chance of getting ovarian cancer.

Your chances may be slightly higher because of your age or race. But if someone in your family has had breast or ovarian cancer, your chances of getting those cancers may be even higher. And the more relatives you have with these cancers, the higher your chances are. Women who have higher chances than normal are said to be “at higher risk.”

If you have a family history of breast or ovarian cancer, it may be important to you to find out how high your risk is so that you can decide whether to do something to lower that risk, like take medicine or have surgery.

The best way to find out about your risk is to talk to your doctor. But you can get some idea of how high your risk is by knowing your family history and understanding how it relates to breast and ovarian cancers.

What is a family history?

Having a family history means that you have one or more blood relatives with breast or ovarian cancer.

  • They may be relatives who have died or relatives who are still alive.
  • They may be first-degree relatives (parents, sisters, brothers, and children).
  • Or they may be second-degree relatives (aunts, uncles, nieces, nephews, and grandparents), or third-degree relatives, which includes first cousins.

Some family histories are stronger than others. Here’s what determines whether 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 relatives there are, the stronger your family history. For example, having one first-degree relative with breast cancer makes you 2 times more likely to get it. But having two first-degree relatives with breast cancer makes you 5 times more likely to get it.1
  • How young these relatives were when they were diagnosed. Having any relatives who were diagnosed before age 50 adds to your risk.
  • Whether you have both breast and ovarian cancer in your family
  • Whether you have a father or brother who had breast cancer. Breast cancer in men is rare, but when it happens in your family, it adds to your risk.
  • Whether you have an Ashkenazi Jewish heritage. Breast and ovarian cancer rates are much higher among Ashkenazi Jews (Jews whose ancestors came from Eastern Europe).

In the tables below, the figures are only rough estimates from research studies. Lifetime risk means the chance that you will get these cancers sometime during your life. These numbers may not apply to you, but they can give you an idea of how high your risk may be.

How does family history affect your lifetime risk for breast cancer?

Average women

12 out of 100 women will get breast cancer.

1 first-degree relative with breast cancer

24 out of 100 women will get breast cancer.1

2 or more first-degree relatives with breast cancer

60 out of 100 women will get breast cancer.1

See a picture that may help you understand how much having a family history can increase your risk for breast cancer.

How does family history affect your lifetime risk for ovarian cancer?

Average women

2 out of 100 women will get ovarian cancer.

1 first-degree relative with ovarian cancer

6 out of 100 women will get ovarian cancer.2

2 or more relatives with ovarian cancer

As many as 47 out of 100 women will get ovarian cancer.2

See a picture that may help you understand how much having a family history can increase your risk for ovarian cancer.

Women with relatives who have had colon cancer also have a higher-than-average chance of getting ovarian cancer.3

Your doctor will ask about at least three generations of your family history and tell you how much it affects your risk. Your doctor may also send you to a genetic counselor, someone who is trained to help people understand their risks for certain diseases.

What is a BRCA gene change?

Sometimes a very strong family history is caused by a mutated gene that runs in the family.

BRCA1 and BRCA2 are genes that normally help control cell growth. But an inherited change, called a mutation, in one of these genes makes you much more likely to get breast and ovarian cancers. BRCA (say "BRAH-kuh") stands for BReast CAncer. A BRCA gene test is a blood test that can tell you and your doctor whether you have one of these changed genes.

Having a BRCA gene change is pretty rare. Most women with a strong family history of breast or ovarian cancer don't have a BRCA gene change.

Before you have a gene test, you will need to see a genetic counselor. Counseling will help you make an informed decision about whether to have a BRCA gene test. It is often covered by insurance, but check with your insurance company to find out for sure.

Ashkenazi Jews are more likely to have one of these BRCA genes. Some experts recommend genetic counseling for Ashkenazi women if they have one or both of the following:4

  • Any first-degree relative with breast or ovarian cancer
  • Two second-degree blood relatives with breast or ovarian cancer

If you are not of Ashkenazi Jewish descent, some experts recommend genetic counseling if you have one or more of the following:4

  • Two first-degree relatives with breast cancer, one of whom was diagnosed before age 50
  • Three or more first- or second-degree relatives with breast cancer, diagnosed at any age
  • Both breast and ovarian cancers in the family
  • A first-degree relative with cancer in both breasts
  • Two or more relatives with ovarian cancer

In the table below, the figures are only rough estimates from research studies. Lifetime risk means the chance that you will get this cancer sometime during your life. These numbers may not apply to you, but they can give you an idea of how high your risk may be.

How does having a BRCA gene change affect your lifetime risk?

 

Breast cancer risk

Ovarian cancer risk

Average women

12 out of 100 women will get breast cancer.

2 out of 100 women will get ovarian cancer.

BRCA gene carriers

36 to 85 out of 100 will get breast cancer.3

16 to 60 out of 100 will get ovarian cancer.3

In the table above, the range for BRCA gene carriers is very broad. That's because different studies have had different results. More study is needed to get a better idea of just how high the risk is for these women.

Pictures may help you understand these numbers better. See the following pictures to get a better idea of how much a BRCA gene change increases your risk for:

If you are worried that you may have a BRCA gene change, talk to your doctor.

Click here to view a Decision Point. Should I have a gene test for breast and ovarian cancer?

How can you find out what effect your family history has on your risk?

The best way to find out is to see your doctor. Your doctor will ask you for as much information about your relatives as you can give (for example, what kind of cancer they had, if any; how old they were when they were diagnosed; and, if they have died, how old they were when they died).

People often don't have a lot of information about all of their relatives. The more you can find out, the better your doctor can help you figure out how strong your family history is.

Your doctor may send you to a genetic counselor, who can help you learn how high your cancer risk is. After counseling, you may decide to have a BRCA gene test.

Finding out how high your risk is can help you make important decisions about your health. Some women decide to take extra steps to prevent breast and ovarian cancer, such as having checkups more often, taking anti-cancer medicine, or having surgery to remove the breasts, the ovaries, or both.

Click here to view a Decision Point. What should I do if I'm at high risk for breast cancer?
Click here to view a Decision Point. Should I have my ovaries removed to prevent ovarian cancer?

References

Citations

  1. American Cancer Society (2009). What are the risk factors for breast cancer? Detailed guide: Breast cancer. Cancer Reference Information. Available online: http://www.cancer.org/docroot/CRI/content/CRI_2_4_2X_What_are_the_risk_factors_for_breast_cancer_5.asp.
  2. Stratton JF, et al. (1998). A systematic review and meta-analysis of family history and risk of ovarian cancer. British Journal of Obstetrics and Gynaecology, 105(5): 493–499.
  3. National Cancer Institute (2002). Genetic testing for BRCA1 and BRCA2: It's your choice. Available online: http://www.cancer.gov/cancertopics/factsheet/Risk/BRCA.
  4. U.S. Preventive Services Task Force (2005). Genetic risk assessment and BRCA mutation testing for breast and ovarian cancer susceptibility: Recommendation statement. Annals of Internal Medicine, 143(5): 355–361.

Credits

Author Bets Davis, MFA
Editor Susan Van Houten, RN, BSN, MBA
Associate Editor Pat Truman, MATC
Primary Medical Reviewer Joy Melnikow, MD, MPH - Family Medicine
Specialist Medical Reviewer Douglas A. Stewart, MD - Medical Oncology
Last Updated August 18, 2009

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