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What is Triple-Negative Breast Cancer?

Triple-negative breast cancer (TNBC) is a less common type of breast cancer in which hormones are not responsible for the growth of the cancer cells and the breast cancer is not over-producing HER2 protein. The more common types of breast cancer are associated with one of the following types of receptors:

  • Estrogen (ER) and progesterone (PR), female hormones
  • HER2, a gene that can play a role in the development of breast cancer

Research has recently proven that TNBC is not a single disease, but rather a group of diseases. Each subtype of TNBC has its own unique makeup that may suggest different therapies are needed for each type. This can make treatment more complex.

Roughly 10 to 15% of breast cancer patients will be diagnosed with triple-negative breast cancer. Younger women (under age 50), and women of both African American and Hispanic descent are typically affected the most. Triple-negative breast cancer may also be associated with having an inherited mutation in the BRCA genes. BRCA1 mutation carriers are more likely to have estrogen receptor negative (ER-), progesterone receptor–negative (PR-), and HER2 receptor-negative (HER2-) breast cancer.

Triple-Negative Breast Cancer Treatment Options

Triple-negative breast cancer is more aggressive than other types of breast cancer because it is more likely to reoccur in other organs such as the bone, liver, lung, and brain. Because TNBC lacks hormone receptors and HER2, hormone therapy (i.e. aromatase inhibitors and Tamoxifen) and targeted therapy, such as Herceptin, are not effective.

While this reduces the number of options for triple-negative breast cancer treatment, it shouldn’t discourage you. Fortunately, triple-negative breast cancer can be treated with a variety of different chemotherapy combinations. Depending on the stage of the cancer, many breast cancer patients, including triple-negative patients, will go through a multimodality treatment plan consisting of chemotherapy, radiation, and surgery. Triple-negative breast cancer, in particular, responds well to chemotherapies such as anthracyclines (Adriamycin), alkylating agents (Cytoxan), and taxanes (Taxol or Taxotere).

Breast cancer doctors are still developing their understanding of triple-negative breast cancer. Clinical trials remain ongoing with promising results in using immunotherapy in combination with chemotherapy to treat triple-negative breast cancer at all stages. Because of this, the treatment options for these patients vary based on the availability of clinical trials and the oncology community’s knowledge on which combination of therapies may be most effective for their patients.

Triple-Negative Breast Cancer Research is Shaping the Future of Treatment

While there is still much to learn about triple-negative breast cancer, there is progress being made. Thanks to ongoing breast cancer research, new therapies have emerged for triple-negative breast cancer in recent years. According to the Breast Cancer Research Foundation, therapies being tested in clinical trials include immunotherapies called immune checkpoint inhibitors, drugs that target the androgen receptor, DNA damaging agents such as platinum drugs, drugs that block DNA repair pathways called PARP inhibitors, and combination approaches.

Recently, olaparib (Lynparza), and talazoparib (Talzenna) are PARP inhibitors used to treat advanced breast cancers with germline BRCA mutations. While this treatment does not help all patients with triple-negative breast cancer, it does provide another treatment option for those whose TNBC is associated with a BRCA gene mutation. Cancer treatment clinical trials that use these, as well as other therapies, could play a key role in providing a more specific treatment plan for triple-negative breast cancers.

If you’d like to learn more about triple-negative breast cancer or would like to receive a second opinion about your treatment options for triple-negative breast cancer, contact the experts at Arizona Oncology. Triple-negative breast cancer clinical trials are also available at select Arizona Oncology locations.

For more information on participating in clinical trials, please ask your breast cancer oncologist. Click here to view a complete list of all of the cancer research trials available through Arizona.

If you have a history of various cancers in your family, you may want to consult with the Arizona Oncology genetic counseling team. Genetic testing is available through many of the Arizona Oncology cancer centers throughout Arizona. Visit this page to learn more about genetic testing.


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