Triple-negative breast cancer (TNBC) is subtype of breast cancer that comprises about 15% of breast cancer cases. Unlike more common forms of breast cancer, TNBC is not fueled by the hormones estrogen or progesterone, nor is its growth supported by the human epidermal growth factor receptor 2 (HER2) protein. Thus, the “triple-negative” in the name refers to tumor cells that lack and test negative for these three molecular substances.
While triple-negative breast cancer is similar to basal-like breast cancer—and the terms are often used interchangeably—they are not exactly the same. Most but not all of triple-negative breast cancers are basal-like breast cancers and vice versa.
Causes of Triple-Negative Breast Cancer
As with all types of breast cancer, what exactly causes triple-negative breast cancer is unknown. But there are some risk factors that increase the chance of developing this type of cancer.
These risk factors include:
- Being Black or Hispanic – Black women are most commonly affected by TNBC, followed by women of Hispanic descent.
- Being younger than 50 – TNBC is more likely to develop in women who are younger than 50, as opposed to more common forms of breast cancer that usually affect women older than 60.
- Having inherited the BRCA1 gene – Women with the BRCA1 (breast cancer gene 1) mutation have been found to be at an increased risk for developing TNBC.
Symptoms of Triple-Negative Breast Cancer
Like most other forms of breast cancer, signs of TNBC involve the presence of a breast lump, and diagnosis in an early stage can lead to a positive prognosis.
Other symptoms can include:
- Discharge from the nipple that is not breastmilk
- Swelling, reddening, dimpling or thickening of breast skin
- Changes in the shape and appearance of the nipples or breast
- Abnormal pain in nipple or breast
Diagnosing Triple-Negative Breast Cancer
Triple-negative breast cancer is diagnosed like some other forms of breast cancer. The process may include:
- A mammogram
- An image-guided biopsy
- Breast MRI
- Molecular breast imaging
- Other tests and imaging modalities
Treatments for Triple-Negative Breast Cancer
Triple-negative breast cancer is difficult to treat and does not respond well to targeted therapies as some other types of cancer do. At Tampa General Hospital’s Cancer Institute, our breast cancer experts review each patient’s diagnostic and genetic reports closely to prepare a treatment plan best suited to a patient.
A treatment plan for triple-negative breast cancer may involve:
- Partial breast irradiation
- Poly ADP-ribose polymerase (PARP) inhibitors
- Neoadjuvant chemotherapy, or chemo administered before surgery