Understanding Your Family History With Breast Cancer

Knowledge is power but choices aren't easy

mother and daughter talking

Jennifer Davis was 19 years old when her mother, then 49, was diagnosed with breast cancer. In a way, it wasn't a surprise. Breast cancer claimed her maternal great-grandmother at age 28. And her maternal grandmother died of ovarian cancer at 69.

Then, as her mother underwent surgery and started chemotherapy, Davis found a lump in her own breast. Although it was benign, she was terrified. "I had just seen my mother go through chemo and I wondered if I was next," recalled Davis, a Washington, DC resident.

Genetic testing confirmed Davis had inherited the gene mutation that increases her risk of developing breast or ovarian cancer. At age 23, she is diligent about screening and a healthy lifestyle, and she is giving serious thought to eventually removing her breasts and ovaries as a dramatic, but effective, preventative measure.

Because genetic testing is still relatively new, researchers aren't sure how many people have one of the gene mutations associated with breast cancer. But, they estimate that up to 30 percent of American women have an immediate family member who was treated for breast cancer.

This means that even young women with a known family history of the disease can start taking steps to protect their own health. However, this also presents tough choices, including whether to undergo prophylactic surgery or take medications that decrease the risk of breast cancer but often have side effects.

1st Degree, 2nd Degree & 3rd Degree Relatives

The average American woman has a 12 percent chance of developing breast cancer in her lifetime. This figure can more than double for a woman with a family history of breast cancer.

According to the U.S. Centers for Disease Control and Prevention, women with a "first-degree" relative—such as a mother or sister—who had breast cancer have an approximately 30 percent chance of developing the disease, too. If that first-degree relative is diagnosed with bilateral breast cancer (breast cancer in both breasts), the risk jumps to 36 percent.

Among those with "second-degree" relatives—grandmother, aunt, or niece—lifetime risk is about 22 percent. For those with a "third-degree" relative—cousin, great-grandparent, or great-aunt—who had breast cancer, the risk is 16 percent.

Yet, family history doesn't guarantee a breast cancer diagnosis. Experts estimate that only five percent to 10 percent of breast cancer cases are hereditary. In addition, the gene mutations associated with an increased risk of breast and ovarian cancer appear to be uncommon in the general population.

These are the gene mutations labeled BRCA1 and BRCA2 by researchers. BRCA stands for breast cancer and the numbers indicate the order researchers discovered the gene mutations.​

Although the exact prevalence of the mutations is unknown, one study found that within a group of approximately 2,300 women, ages 35 to 64, about 2.9 percent of white women, 1.4 percent of black women, and 10.2 percent of Jewish women had BRCA1 mutations. The study also found that 2.6 percent of black women, 2.1 percent of white women, and 1.1 percent of Jewish women had the BRCA2 mutation.

Genetic Testing

Many physicians now advise women with a family history of either breast or ovarian cancer to pursue genetic testing. This personal decision can bring its share of emotions as well as useful information.

According to a Canadian study of 39 people who tested positive for the gene mutation, the majority viewed the results as enabling. Participants said the testing allowed them to take a more proactive approach to their health care.

But, a minority expressed feelings of hopelessness and uncertainty. These individuals said they felt "neither ill nor completely well." 

In addition, while health insurance and discrimination were previously concern, the Genetic Information Nondiscrimination Act of 2007-2008 now ensures nationwide protection 

Earlier Screening

For most women under age 35, breast cancer screening is not part of their annual health routine. But, for women with a family history of breast cancer, experts say screening should begin as early as age 25.

Memorial Sloan-Kettering Cancer Center recommends that women who have a first-degree relative diagnosed with breast cancer should begin yearly mammograms starting 10 years earlier than when the youngest family member was diagnosed.

For example, if a mother was diagnosed at age 42, her daughter should begin annual mammography testing at age 32. For women in this risk factor group, experts also recommend clinical breast exams at least twice each year and monthly, with self-exams beginning at age 20.

There is some debate about the role MRIs should play in breast cancer screening. Some studies have shown that MRI screening is more effective than other diagnostic techniques. Doctors at Sloan Kettering recommend that women with a family history have both an MRI and a mammogram annually. However, no studies have correlated MRI screening with a decrease in breast cancer deaths.


Research shows that smoking and a fatty diet contribute further to one's risk of cancer. So, a healthy lifestyle is especially important for someone with a family history of the disease.

Chemoprevention is another course of action. Some of the same drugs prescribed to prevent a recurrence are also given to women hoping to avoid breast cancer, but only for those over the age of 35.

These drugs block the activity of the female hormone estrogen, believed to stimulate some types of cancer. But that means they can also affect fertility, so they are not approved for use by younger women of reproductive age.

For women over 35, studies have shown these drugs—Tamoxifen (Nolvadex) and Evista (Raloxifene)—can decrease the risk of invasive breast cancer by as much as 50 percent. And, they can decrease the risk of noninvasive breast cancer by 30 percent. However, they are not without side effects—some of which mimic the symptoms of menopause, including weight gain, hot flashes, and vaginal dryness.

An extreme, but effective method of prevention is ​the removal of one or both breasts before cancer develops. Researchers estimate that surgery reduces the risk of breast cancer by 90 percent. Removing the ovaries is another effective surgery, but one fraught with emotion, especially for young women who one day hope to have children.

A Word From Verywell

Davis, who tested positive for the BRCA1 mutation, was advised by her genetic counselor to have her children young, then have her breasts, ovaries, and uterus removed—all before she's 35. Even at 23 years old, she worries about being able to accomplish that goal. But she still believes that the surgery will bring her a sense of relief. So, take the time to consider each option carefully and seek the advice of a trusted physician or genetic counselor in the decision-making process.

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