Hereditary Risks for Triple Negative Breast Cancer

March 3 is Triple Negative Breast Cancer Day, so we want to discuss the important association of a breast cancer susceptibility gene (BRCA1) and Triple Negative Breast Cancer. 

Changes (or mutations) in the BRCA1 and BRCA2 genes can predispose to a higher risk for some types of cancer, including breast, ovarian cancer, prostate, and pancreatic cancer. 

What is Triple Negative Breast Cancer?

Triple Negative Breast Cancer (TNBC) is a type of breast cancer that is negative for the three common hormonal receptors (estrogen-receptor (ER), progesterone-receptor (PR), and human epidermal growth factor-2 (HER-2)).   

TNBC can be a very aggressive cancer, and there may also be an increased risk of recurrence after treatments. Knowing about an increased risk of TNBC due to BRCA1 is an important step in prevention. Strategies for lowering your risk for cancer or detecting it at its earliest, most treatable stage, include intensive screening and risk-reducing surgery. 

How would one know if they have an increased risk to carry a BRCA1 gene mutation? 

Genetic counselors and other health care providers will look for “clues” that may indicate that there is an increased risk for a gene change in a gene such as BRCA1 running in a family. We discussed the diagnosis of TNBC being an indicator, other important signs include: 

Family History: Family history is another major clue for a potential underlying hereditary cancer predisposition syndrome. A trained healthcare professional such as a genetic counselor will look for certain patterns that can suggest hereditary risk. Typically they are looking for how many people have had cancer in the family, the ages those people developed cancer, if there is a possible pattern of inheritance of cancer in the family, and if the types of cancers are associated with any of the known hereditary cancer genes. For example, breast and ovarian cancer can be seen in Hereditary Breast and Ovarian Cancer syndrome (BRCA1 and BRCA2 genes); breast, uterine, and thyroid cancers can be seen in Cowden syndrome (PTEN gene), and later-onset bilateral breast cancers and colon cancers can be seen with CHEK2 gene mutations.

Some individuals have limited information about their family history, which could be due to adoption, falling out of touch, or difficult family dynamics, among other things. Other individuals may have a limited family history of cancer but also have a very small family. These factors can make it difficult to accurately determine how high the risk is for certain cancers within a family. If you have a limited or unknown family history, a genetic counselor or other trained healthcare professional can help determine whether genetic testing would be recommended for you.

Unusual Cancer Diagnoses: Bilateral breast cancer (breast cancer in both breasts), multiple cancers in the same person, male breast cancers, or other unusual presentations of cancer can be red flags that there is a genetic or hereditary risk for cancer in the family.

Ethinicity: Our ethnic backgrounds can influence our risks for many different genetic conditions, including cancer. For example, changes in the BRCA1 and BRCA2 genes are relatively uncommon in the general population (~1 in 400 people). In people who have Ashkenazi Jewish ancestry, their chance to carry a mutation in BRCA1 or BRCA2 could be as high as ~1 in 40.

It is important to remember that only about 5-10% of cancer is strongly hereditary. The vast majority of cancer (~75-80%) is sporadic and not due to an identifiable genetic risk that runs in the family. If you are concerned that your personal or family history may fit the pattern of a hereditary cancer syndrome, you may benefit from an evaluation by a genetic counselor. 

Please contact the experts at Genetic Support Foundation for any questions or to schedule an appointment. 

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