Topic Overview

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

But if someone in your family has had breast or ovarian cancer, your chances of getting those cancers may be higher. And if you have 2 or 3 relatives who have had these cancers, your chances may be even higher.

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.
• 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. Having both adds to your risk.
• 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.