Health library

Learn how family history can affect your chances of having breast cancer and what options may be available to those at higher-than-average risk.

Learning that a close family member has breast cancer can leave you understandably distressed. In addition to being concerned about your loved one's health, you might also be wondering how the diagnosis will affect your personal risk for breast cancer.

While it's true that a family history of breast cancer can raise your risk, it doesn't mean that you will necessarily develop the disease—or that you need to take extra steps to protect yourself.

You will, however, want to share the details of your family history with your doctor. He or she can help you determine if your risk is high enough to warrant taking additional steps, such as getting extra screening tests or being tested for an inherited gene mutation.

How family history can affect your risk

For family history to raise your breast cancer risk, a close relative—such as a mother, father, sibling, child, aunt or grandmother—needs to have had breast cancer.

But even then, how much family history affects your risk may vary, depending on factors such as the number of relatives affected and their ages when diagnosed. Consider a woman whose mother had breast cancer at age 70: "Her risk is barely more than another woman her age who doesn't have that in her family," says Debbie Saslow, PhD, regional medical scientific director at Merck.

According to Dr. Saslow and the American Cancer Society (ACS), factors in your family history that may have a significant effect on your risk include:

• Having a first-degree relative—a mother, a sister or a daughter—with breast cancer.
• A family history of ovarian cancer.
• Breast cancer in a close male relative.
• A close relative who had cancer in both breasts.

A family history of breast cancer can indicate increased risk for a variety of reasons. For example, it may point to shared lifestyle traits that may increase risk, such as not exercising or being overweight.

A family history is also a signal that you might have inherited a genetic predisposition toward breast cancer, according to Dr. Saslow.

The genes most often linked to breast cancer are called BRCA1 and BRCA2. More than 60% of women who inherit a harmful change in BRCA1 and BRCA2 mutation will develop breast cancer during their lifetime, the National Cancer Institute (NCI) reports. That means women with certain inherited mutations are much more likely to develop breast cancer than women who don't have such a mutation. Gene mutations also put women at higher risk for developing breast cancer at a young age.

Genetic testing can help identify BRCA1 and BRCA2 mutations. But such tests aren't appropriate for every woman who has a family history of cancer. Whether to have genetic testing done is a personal decision involving many factors, Dr. Saslow notes, but if you have a strong family history of breast cancer you may be a candidate. Women will want to weigh the risks and benefits and speak with a genetic counselor.

Lowering your risk

While your family history and your genes are beyond your control, there are steps you can take to protect your health.

For example, research suggests that lifestyle changes, such as exercising regularly, maintaining a healthy weight and avoiding alcohol, may help—though it's not yet known if these steps benefit women who have a gene mutation, according to the NCI.

In addition, if you do have a gene mutation or a strong family history of breast cancer, your doctor can also talk to you about specific steps for women at high risk, such as:

Extra screening. Your doctor may suggest that you start screening earlier than is recommended for women at average risk, and that you consider screening with breast MRI or ultrasound in addition to mammography.

Medicines. Drugs such as tamoxifen and raloxifene can reduce breast cancer risk, studies show. Women and their doctors should discuss the risks and benefits of preventive medicines, which may have serious side effects.

Surgery. Some women at very high risk choose preventive surgery to remove the breasts before cancer might develop. Before making such a decision, you'll want to carefully consider and discuss your options with your healthcare team.

Talk to your family

Breast cancer isn't the only disease that has a family connection. Heart disease, diabetes and other forms of cancer can also run in families. To help people learn more about their family health history, the Office of the Surgeon General and other U.S. government agencies have launched the Family History Initiative.

Reviewed 9/22/2024