Triple-negative breast cancer (TNBC) is breast cancer that does not have progesterone or estrogen receptors and does not make much, if any, of the HER2 protein. When your tumor cells are tested, they are negative for estrogen, progesterone, and HER2. TNBC may also be called ER/PR negative and HER2 negative.

TNBC makes up about 10 to 15 out of 100 cases of breast cancer.
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 treatments you will have and how well they work depend on the size and extent of your cancer.

How is TNBC diagnosed?

During a breast biopsy or surgery, a sample of the tumor will be removed. It is sent to a lab and 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 called a subtype of breast cancer called triple-negative. Knowing this will help plan your treatment.

How is TNBC treated?

Chemotherapy, radiation, and surgery are most often used to treat triple-negative breast cancers.
Research has found that having chemotherapy before surgery (called neoadjuvant) better treats TNBC.
Hormone therapy and HER2 targeted therapies are not used to treat TNBC since the tumor cells do not have the receptors that these medications work on.
If you have advanced or stage IV (four) 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 (four) 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?

A cancer diagnosis can be challenging. Talk to your team about your treatment options and your goals. Below are resources that can help support you and your loved ones.

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/