Triple-Negative Breast Cancer
About 15 to 20 percent of breast cancers are triple-negative. But you may have never heard of triple-negative breast cancer before you got your test results. Knowing the basics of breast cancer can help you understand how triple-negative breast cancer is different from other types of breast cancer.
To find out which type of breast cancer you have, your doctors search for the presence or absence of three receptors. Receptors are proteins that live inside or on the surface of a cell and bind to something in the body to cause the cell to react. The three receptors are:
- the estrogen receptor, or ER
- the progesterone receptor, or PR
- the human epidermal growth factor receptor 2, or HER2
In ER-positive breast cancer, PR-positive breast cancer and HER2-positive breast cancer, treatment includes medicines that prevent, slow or stop cancer growth by targeting those receptors. But triple-negative breast cancers need different types of treatments because they test negative for all three receptors. Medicines such as tamoxifen, which targets the estrogen receptor, and trastuzumab (Herceptin), which targets HER2, are not helpful in triple-negative breast cancer. Instead, chemotherapy has been shown to be the most effective treatment.
Researchers are learning more about triple-negative breast cancers, including how they behave and what puts people at risk for them. The goal is to find the best ways to use existing treatments and to develop new ones.
- whether the cancer has traveled to the lymph nodes near your breast
- the size of the main tumor
- details in your pathology report, such as tests of the tumor grade, which shows how quickly the cancer cells are dividing
Most triple-negative breast cancers have a basal-like genetic pattern. This means the cells look somewhat like the cells that line the breast ducts, the tubes in the breast where milk travels.
Basal-like breast cancers tend to overexpress, or make too much of, certain genes that encourage cancer growth. Not all triple-negative breast cancers are basal-like, and not all basal-like breast cancers are triple-negative. About 70 to 90 percent of triple-negative breast cancers are basal-like.
Doctors choose treatments because the cancer is triple-negative, not because it’s basal-like. The basal status of the cancer does not factor into treatment decisions. Still, your doctor may tell you the cancer is basal-like because you may see the term as you research triple-negative breast cancer.
Myth #1: Women with triple-negative breast cancer can have the same treatments as all other women with breast cancer.Fact: Many people do not understand there are different types of breast cancer. You might know women who took a hormonal therapy pill for 5 to 10 years to protect against recurrence. These women, and some others, may not understand that this option does not exist for you. On the other hand, you may take some of the same chemotherapy medicines as women with other types of breast cancer.
Myth #2: Triple-negative breast cancers are always hard to treat.Fact: Your doctor may tell you triple-negative breast cancer is “harder to treat” than other types of breast cancer. Many triple-negative cancers are aggressive, but your doctor’s prediction of how well your treatment may work depends not only on its triple-negative status but also on the tumor size and whether the cancer has traveled to the lymph nodes in your armpit. There are some very effective treatments for triple-negative breast cancer.
Myth #3: Only African-Americans get triple-negative breast cancer.Fact: While breast cancers in African-American women are more likely to be triple-negative than those in white women, triple-negative breast cancers affect women of all races.