Your pathology report may say that the breast cancer cells tested negative for estrogen receptors (ER-), progesterone receptors (PR-), and HER2 (HER2-). Testing negative for all three means the cancer is triple-negative.
These negative results mean that the growth of the cancer is not supported by the hormones estrogen and progesterone, nor by the presence of too many HER2 receptors. Therefore, triple-negative breast cancer does not respond to hormonal therapy (such as tamoxifen or aromatase inhibitors) or therapies that target HER2 receptors, such as Herceptin (chemical name: trastuzumab). However, other medicines can be used to treat triple-negative breast cancer.
About 10-20% of breast cancers — more than one out of every 10 — are found to be triple-negative. For doctors and researchers, there is intense interest in finding new medications that can treat this kind of breast cancer. Early studies are trying to find out whether certain medications can interfere with the processes that cause triple-negative breast cancer to grow. In this section, you can learn about:
- What Is Triple-Negative Breast Cancer?
- Who Gets Triple-Negative Breast Cancer?
- Treatment for Triple-Negative Breast Cancer
- Research on New Treatments for Triple-Negative Breast Cancer