Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is breast cancer that does not have progesterone or estrogen receptors and does not produce much, if any, of the HER2 protein. This is called ER/PR negative and HER2 negative or “triple-negative” breast cancer (TNBC). All three tests (estrogen, progesterone, and HER2) are negative.

• TNBCs make up about 10-15% of all breast cancers.
• It is more common in those who are BRCA1 positive or have not gone through menopause yet, and in African-American women.
• Breast cancers in Latina women have a higher chance of being triple-negative.
• Some cancers need estrogen, progesterone and/or HER2 to grow. TNBC does not.
• TNBC can be more aggressive and recur (come back) more often than other breast cancers. The size and extent of your cancer plays a big role in which treatments you will have and how well they will work.

How is TNBC diagnosed?

• After a breast biopsy or surgery, a sample of the tumor is tested for hormone receptors (estrogen and progesterone) and HER2. These will be listed in your pathology report.
• If the sample is negative for hormone receptors and HER2, the cancer is triple-negative.
• Finding out the subtype of your breast cancer is important for treatment planning.

How is TNBC treated?

• Chemotherapy, radiation, and surgery are most often used to treat triple-negative breast cancers.
• Research has found having chemotherapy before surgery (called neoadjuvant) works better for treating TNBC.
• Hormone therapy and HER2 targeted therapies are used to treat some breast cancers but are not used in the treatment of TNBC. TNBC tumor cells do not have the receptors that these medications work on.
• If you have advanced or stage IV TNBC and have a BRCA 1 or 2 mutation, you may also be treated with targeted therapies called PARP inhibitors (olaparib and talazoparib).
• Patients with stage IV TNBC will also be tested for PD-L1 proteins. If these proteins are found on the cancer cells, you may be treated with the immunotherapy medication atezolizumab along with chemotherapy.

How can I manage this diagnosis?

• While the diagnosis of TNBC may be hard, remember there are many treatment options.
• Learn about TNBC. This can help you ask questions at your visits and feel more in control of your treatment decisions.
• Look for support groups that discuss TNBC. There are many online groups and websites (see resources below).
• All cancers are unique and you should not compare your experience to others.

Resources for More Information

Triple-Negative Breast Cancer Foundation

Offers education, support/helpline, and online forum.

https://tnbcfoundation.org/

Living Beyond Breast Cancer

Offers education and a “buddy” program that can match you with another woman who has had a diagnosis of TNBC.

https://www.lbbc.org/