Triple-Negative Breast Cancer
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In triple-negative breast cancer (TNBC), the cancer cells do not contain receptors for estrogen, progesterone, or HER2. About 10% to 20% of all breast cancers are triple-negative. This type of breast cancer is usually invasive and usually begins in the breast ducts.
Healthy breast cells contain receptors for the hormones estrogen and progesterone. They also contain receptors for a protein called HER2, which stimulates normal cell growth. About 2 out of 3 women with breast cancer have cells that contain receptors for estrogen and progesterone, and about 20% to 30% of breast cancers have too many HER2 receptors. Breast cancer that is estrogen receptor (ER) and progesterone receptor (PR) positive can be treated with hormonal therapies. Breast cancer with excess amounts of HER2 can be treated with anti-HER2 drugs such as trastuzumab.
In women with TNBC, the malignant cells do not contain receptors for estrogen, progesterone or HER2. Breast cancer that is ER, PR and HER2 negative cannot be treated with hormonal therapies or medications that work by blocking HER2, such as trastuzumab.
Fortunately, triple-negative breast cancer can be treated with other drugs, such as chemotherapy, radiation, and targeted therapies.
Triple-Negative Breast Cancer Risk Factors
Any woman can get TNBC. Certain features that may increase risk include:
Age: Women under age 40 – 50 are more likely to get triple-negative breast cancer than women over age 60.
Race: Triple-negative breast cancer is more common among African American and Hispanic women than among Asian and non-Hispanic white women.
BRCA1 Mutation: BRCA1 and BRCA2 are genes that help repair damaged DNA. Mutations in BRCA1 and BRCA2 can be inherited from a family member. Women with the BRCA1 gene mutation have a higher risk of developing TNBC.
Triple-Negative Breast Cancer Symptoms
Although TNBC does not look different from other breast cancer, it has several unique characteristics, including:
Receptor status: Tests that detect receptors for estrogen, progesterone and HER2 will be negative, which means hormone therapy, a traditional breast cancer treatment, is not effective. Instead, triple-negative breast cancer treatment options include chemotherapy, targeted therapy and radiation.
More aggressive: A greater tendency to spread and recur after treatment compared to other breast cancer types. This risk decreases after the first few years following therapy.
Cell type and grade: Triple-negative breast cancer cells tend to be “basal-like,” meaning that they resemble the basal cells lining the breast ducts. The cells may also be higher grade, which means that they no longer resemble normal, healthy cells.
Triple-Negative Breast Cancer Treatment
Because TNBC cannot be treated with hormonal or anti-HER2 therapies, it has become associated with a poorer prognosis. But TNBC is treatable, and women diagnosed with this disease can be cured. Women with TNBC are also spared the unpleasant side effects of hormonal therapies. Triple-negative breast cancer treatments may include:
Chemotherapy: TNBC tumors tend to be more susceptible to chemotherapy than tumors that are positive for ER, PR and HER2. If you are disease-free for four or more years following chemotherapy, it is unlikely that your cancer will return.
Immunotherapy: Although anti-HER2 drugs like trastuzumab cannot be used in TNBC, other biologic, or targeted, drugs can be combined with chemotherapy. Targeted therapy drugs that may be used to treat TNBC include bevacizumab, erlotinib, and cetuximab, among others.
Radiation Therapy: Women with triple-negative breast cancer may also undergo radiation to help ensure that any cancer cells remaining in the body after chemotherapy are destroyed.
Your doctor will explain the many treatment options for TNBC, and can also help you find clinical trials where the latest triple-negative breast cancer treatments are being explored.