Your Risk of Breast Cancer if Your Mother Had Breast Cancer

How her disease (and your overall family history) impacts you

Woman hugging her mother in the kitchen
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Having a mother with breast cancer increases the chance that you could also develop the disease. While most breast cancer is actually not hereditary, it is valuable to know if you have family members who were ever diagnosed with the disease. Women who have a mother, sister, or daughter who developed breast cancer at a young age (premenopausal) have double the risk of the disease compared to those who don't have this family history.

With new genetic testing techniques, breast cancer genes can be identified even before the disease develops. However, such testing is imperfect in terms of determining your risk. While a breast cancer gene increases the chance you'll develop the disease—whether you have a family history of breast cancer or not— not having such a gene does not mean you are necessarily in the clear.

Family History and Breast Cancer Risk

Breast cancer is the most common cancer among women, affecting one in eight (12 percent) throughout their lifetimes. A family history of the disease does increase your risk, but by how much depends on who in your family had breast cancer.

Here's a general sense of how family history affects a woman's risk of breast cancer:

Family History of Breast Cancer Your Breast Cancer Risk (Approx.)
First-degree relative (parent, sibling, or child 24 percent
Two first-degree relatives 36 percent
Second-degree relative (grandparent, aunt, uncle, niece, nephew) 22 percent
Third-degree relative (great-grandparent, cousin, great aunt or uncle) 16 percent

Prostate cancer in male relatives also increases your risk of breast cancer, but the percent increase is not known.

Breast cancer or prostate cancer in younger relatives (premenopausal or under the age of 50) raises your risk more than having older relatives with these conditions.

Collecting Your Family History

Your mother is an important figure in your cancer risk profile if she has or has had breast cancer. But, given the above, it's also helpful to find out if cancer has affected other family members, including grandparents, aunts, uncles, and cousins. Don't assume that you know this information—it's worth specifically asking.

For the purpose of building your own family history, you need to know:

  • What type of cancer a relative had
  • What age they were diagnosed
  • If they were cured, still living with cancer, or have died

Other details, such as the grade, type, and stage of cancer are not as important for you to know. If you develop breast cancer, your medical team will identify your own grade, type, and stage rather than relying on your family history.

If your mother or father are alive and able to share your family's background with you, filling out the Cancer Family History Questionnaire that was created by the American Society of Clinical Oncology can help you keep track of the information. Once you gather your family history, it would be useful to keep that record for yourself and for other family members who share some of your family medical history.

Conversations About Cancer

It's also important to consider connecting with your family members by asking about more than just the facts about their illness.

  • How did they deal with the fear and uncertainty?
  • Who did they lean on for support?
  • How did they celebrate getting healthy?

Let them talk about the obstacles they overcame and the things they learned about life as they fought their illness. While these conversations won't add facts about your health, they offer a valuable opportunity to bond.

Don't be surprised if a relative—your mother, especially—isn't immediately forthcoming about sharing her cancer story. In addition to the topic possibly being a sensitive one personally, there may be a hesitancy to cause you distress. Express how important it is to you to hear this information and be as supportive as possible as it is shared.

Using Your Family History

You should certainly share your family history with your medical team. Your doctors might advise genetic counseling or genetic testing if your family history suggests that you could be carrying a breast cancer gene.

Some red flags include:

  • Cancer of any kind before the age of 50 (you)
  • More than one relative with the same type of cancer
  • One family member who has more than one type of cancer
  • A family member who has cancer not typical for that gender, such as breast cancer in a male
  • Certain combinations of cancer, such as the combination of breast cancer with ovarian cancer, uterine cancer, colon cancer, prostate cancer, pancreatic cancer, or melanoma
  • Cancer in both of one organ, for example, bilateral breast or ovarian cancer

When You Can't Find Your Family History

While many women already know if their mother, sister, or daughter have had breast cancer, you might not have this information.

If your close family members passed away at a young age, if some of them didn't have access to health care (and might not have been diagnosed), if you were adopted, or if members of your family have been otherwise separated, you might not know which illnesses run in your family.

While family history is important information, breast cancer screenings (mammograms and breast self-examinations) are the most important tools for early detection, whether or not you have a family history of the disease.

Genetic Testing

There are a number of genes associated with breast cancer. The most common of these are BRCA1 and BRCA2 mutations, but there are over 70 identified gene mutations associated with breast cancer, some of which are described as non-BRCA gene mutations. And there is a link between breast cancer genes and the outcome of the disease.

While your family history is a record of the diseases that your family members were diagnosed with, genetic testing is a bit different.

You could have inherited a gene for breast cancer even if no one in your family ever had the disease. And you could have a hereditary tendency to develop the condition even if you don't have an identifiable breast cancer gene.

With this in mind, genetic testing requires a complex decision-making process. The genes you should be tested for and the overall value of the test depend on a number of factors, including your age, health history, family history, race, and ethnic background. For example, an at-home genetic test identifies breast cancer genes that are more common among Ashkenazi women but are rare in other ethnic populations.

Genomic testing and whole exome sequencing are genetic tests that can provide you with information about all of your genes, not just breast cancer genes. This type of testing can be useful, but the cost might not be covered by your health insurer. Furthermore, "good" results can provide a false sense of security—you can develop breast cancer even if you don't have a known breast cancer gene.

A Word From Verywell

Whether you have a family history of breast cancer or not, there are ways for you to lower your own risk. Make sure that your healthcare team knows if your mother, sister, daughter, or other family members had this disease or if you or any of your relatives carries a gene for the disease. And definitely, don't skip your annual screenings.

More and more women and men are getting diagnosed with breast cancer at an earlier stage, receiving more effective treatment, and surviving for years after the diagnosis. You certainly need to be vigilant if you have a family history of breast cancer, but there is no need to live in fear.

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