In metastatic breast cancer, or stage IV disease, the cancer cells have traveled from the breast and nearby lymph nodes and formed tumors in tissues or organs far away from the breast. Metastatic breast cancer can be:
- Hormone receptor-positive
- Both hormone receptor-positive and HER2-positive
If you are diagnosed with metastatic triple-negative breast cancer, or TNBC, it means the stage IV breast cancer is not hormone-sensitive and does not have high levels of the HER2 protein. Triple-negative breast cancer can be treated with chemotherapy. You can find more information on how metastatic breast cancer is diagnosed on our pages about Metastatic Breast Cancer and Testing.
If you had early-stage triple-negative breast cancer, the metastasis is likely to be triple-negative as well. Your medical oncologist may recommend you have a biopsy of any abnormal finding from an imaging test. The biopsy helps to:
- Diagnose the cancer
- Confirm the cancer is metastatic
- Check the receptor status to make sure it did not change from your original diagnosis
Receiving a diagnosis of metastatic triple-negative breast cancer can feel scary. TNBC does not respond to hormonal or HER2-targeted therapies. Since only 15 to 20 percent of breast cancers are triple-negative, you may feel alone.
It may be helpful to understand that many chemotherapy options are available to treat triple-negative breast cancer, and other medicines can lessen side effects. People with TNBC are educating the public about this diagnosis, while doctors and researchers are actively focused on finding new treatments.
One myth about treating metastatic TNBC is that there aren’t effective treatment options. The truth is that an array of treatments can improve your care. Your treatment options include many chemotherapy medicines and may also include targeted therapies that treat some triple-negative breast cancers with specific features.
How do you choose from the many available chemotherapy options? It is important to talk with your doctors about how you wish to balance the goals of keeping the cancer under control as long as possible and maintaining your quality of life, or overall enjoyment of life.
Another important point about treating metastatic TNBC is that if you had early-stage disease, you can retry medicines you were treated with before. A certain treatment may have failed to get rid of the primary disease, but that treatment could still control it in the metastatic setting.
Common chemotherapy treatments for metastatic triple-negative disease are:
- Anthracyclines, which kill cancer cells by stopping cell growth. Three anthracyclines used in metastatic breast cancer are:
- Taxanes, which slow or stop tumor growth by stopping cells from dividing. Three taxanes given for metastatic disease are:
- Platinum-based chemotherapies, which interfere with the action of DNA inside cancer cells. Some platinum-based medicines are:
Other chemotherapy treatments are:
- Capecitabine (Xeloda), given alone or with docetaxel or paclitaxel, is effective against some cancers that stop responding to anthracyclines or taxanes.
- Vinorelbine (Navelbine) prevents the function of microtubules, which help cancer cells divide. It can be used alone or with other chemotherapy medicines.
- Gemcitabine (Gemzar) works by starving cancer cells of the nutrition they need to grow. Gemcitabine, given with paclitaxel, is FDA approved for use when an anthracyline stops working or you can’t take it for other reasons.
- Ixabepilone (Ixempra) stops the growth of tumor cells by targeting a protein called tubulin that helps cells multiply. It is approved for use when other chemotherapy medicines don’t work against the cancer or when the cancer stops responding to treatment.
- Eribulin (Halaven) stops the cancer cells from dividing into new cells by interfering with the parts of the cell that help move the information inside them during cell division. It is approved for use in people whose metastatic breast cancer has grown after treatment with at least two other types of chemotherapy, including an anthracycline and taxane.
In recent years, the FDA has approved treatments that target specific features of some, but not all, triple-negative breast cancers. These are often given alongside chemotherapy. Your doctors can run tests to see if these medicines are appropriate for your treatment.
There are two immunotherapies, medicines that prompt your body’s immune system to recognize breast cancer cells as a disease and kill them:
- Pembrolizumab (Keytruda) is approved for any metastatic breast cancers that are microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR). It is given alongside chemotherapy if the cancer has grown after previous treatments.
- Atezolizumab (Tecentriq) is approved to treat metastatic triple-negative breast cancer that expresses the PD-L1 protein. It is given with the chemotherapy nab-paclitaxel.
Other treatment options include:
- Olaparib (Lynparza) is part of a family of medicines called PARP inhibitors that cause cancer cells to die by stopping the PARP enzyme from repairing cancer cell DNA. It is given to people who have tested positive for a mutation in either the BRCA1 or BRCA2 gene and who have already had cancer grow while on treatment with chemotherapy.
Research is underway to find subtypes of TNBC that respond to new and emerging targeted treatments. You may consider taking part in a clinical trial, a study that looks at how well new medical approaches work in people. Clinical trials offer access to new treatments that are not otherwise available and may prove to work better than standard treatments. Participating in a clinical trial also helps researchers develop better treatments for people diagnosed in the future.