UNDERSTANDING DIFFERENT BREAST CANCER TYPES
One of the ways breast cancers are classified is by proteins, called receptors. There are thousands of different types of receptors on cells in the body. Some receptors are found on the cancer cell surface. Knowing which receptors are present helps your doctor choose a treatment that your type of cancer is most likely to respond.
HR+ breast cancer
Cancers are called hormone receptor-positive (HR+) if they have estrogen or progesterone receptors. When the estrogen or progesterone attach to these receptors, they fuel the cancer growth. Breast cancers that have estrogen receptors are called estrogen receptor-positive (ER+). Breast cancers that have progesterone receptors are called progesterone receptor-positive (PR+).
Treatment for HR+ breast cancers may include medicines that block the effect of estrogen or progesterone.
HER2+ breast cancer
Some breast cancers are fueled by a different receptor called HER2. Both normal cells and cancer cells have HER2 receptors. In HER2+ breast cancer, cancer cells have more HER2 receptors than normal cells.
Treatments for HER2+ breast cancer target and block the HER2 receptor.
Triple-negative breast cancer
Some breast cancers do not have estrogen or progesterone receptors (ER- or PR-). They also do not have too much HER2 (HER2-). This is called triple-negative breast cancer (TNBC).
Hormone therapy is typically not helpful in TNBC because the cancer cells do not have hormone receptors. Drugs that target HER2 are not helpful because the cancer cells have an insufficient number of HER2 receptors.
More about TNBC
- When comparing age groups, the majority of TNBC cases are diagnosed in women 51-60 years old
- However, when women under 40 are diagnosed with breast cancer, it is more likely to be TNBC than if they are diagnosed over 40
- TNBC more commonly affects African American and Hispanic women
- In addition, breast cancers associated with a BRCA mutation (either BRCA-1 or BRCA-2) are often, but not always, triple negative
BRCA=BReast CAncer susceptibility gene;HER2=human epithelial growth factor receptor 2.