Triplenegative

Triple-negative is a clinical designation most often used for breast cancer. It refers to tumors in which the cancer cells do not express three receptors found on or inside the cells: estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). In practice, the term describes ER-negative, PR-negative, and HER2-nonamplified cancers identified by standard pathology testing.

In breast cancer, triple-negative breast cancer (TNBC) accounts for about 10-20% of cases, with a higher incidence among younger patients, women of African descent, and individuals with BRCA1 mutations. These tumors are often high grade and proceed more aggressively, with a greater risk of early recurrence and metastasis compared with other subtypes.

Because they lack ER, PR, and HER2, TNBCs do not benefit from hormonal therapies or HER2-targeted drugs. Diagnosis relies on pathology: immunohistochemistry for ER and PR, and in situ hybridization or alternative tests for HER2. Receptor status guides treatment decisions.

Treatment primarily involves standard cancer therapies such as surgery and radiation, together with systemic chemotherapy. Neoadjuvant chemotherapy is common to shrink tumors before surgery, and achieving a pathological complete response is linked to better outcomes. In recent years, immunotherapy and PARP inhibitors have provided additional options for selected patients.

TNBC is biologically heterogeneous. The basal-like gene expression profile overlaps with TNBC but is not identical; not all TNBCs are basal-like, and not all basal-like cancers are triple-negative. Ongoing research seeks targeted therapies, including antibody-drug conjugates and combinations of chemotherapy with immune checkpoint inhibitors.