Triple-negative breast cancer, or TNBC, is a form of breast cancer that tests negative for estrogen receptors, progesterone receptors, and the HER2 protein. This combination means that TNBC may not respond to some of the hormonal or targeted therapies used in other breast cancer subtypes. Because of its biology, TNBC can behave more aggressively and may spread early, which makes timely diagnosis and a clear treatment plan essential. The information here aims to help patients and caregivers understand common symptoms, diagnostic steps, and the range of treatments that specialists may consider. It also points to reliable resources and practical ways to navigate care and access clinical trials.
Symptoms of TNBC commonly align with breast changes that patients notice themselves. A new lump or thickening in the breast or under the arm can be a warning sign. Changes in the size or shape of the breast, dimpling of the skin, or a nipple that becomes inverted are others to watch for. Nipple discharges that are not breast milk, especially if persistent, can also occur. While breast pain is not as common as a lump, it can accompany other symptoms. Because these signs may arise from conditions other than cancer, any persistent change should be evaluated promptly by a clinician. Increases in breast firmness, swelling, or skin changes such as redness or scaliness can indicate a need for imaging and a biopsy to determine whether cancer is present and what receptors it expresses.
Diagnosis usually begins with a physical exam and imaging tests, such as mammography and ultrasound. When an area of concern is found, a biopsy is performed to examine cells directly. The biopsy results determine receptor status and confirm whether a tumor is TNBC. Additional testing, including genetic testing for BRCA mutations, may be recommended because these mutations can influence treatment choices. Staging tests, such as MRI, CT, or PET scans, help determine whether cancer has spread. A comprehensive plan is then built by a medical team specializing in breast oncology, often at a cancer center or academic medical institution.
Treatment for TNBC relies heavily on chemotherapy, both before and after surgery in many cases. Neoadjuvant chemotherapy, given before surgery, can shrink tumors and improve the feasibility of breast-conserving surgery while providing early information about how the cancer responds to systemic therapy. Adjuvant chemotherapy follows surgery to reduce the risk of recurrence. The decision between lumpectomy and mastectomy, and whether to incorporate radiation, depends on tumor size, location, genetic factors, patient preference, and overall health. Radiation therapy is frequently used after lumpectomy and may also be considered after mastectomy in certain circumstances to eliminate residual microscopic disease.
Because TNBC lacks the three receptors targeted by common hormonal therapies, other strategies are considered. For patients with BRCA gene mutations, PARP inhibitors such as olaparib or talazoparib can be active options, particularly in advanced settings or as maintenance after initial treatment. Immunotherapy has emerged as a meaningful addition in some TNBC cases. Checkpoint inhibitors such as pembrolizumab or atezolizumab, used in combination with chemotherapy, may be offered if the tumor expresses certain biomarkers or in specific clinical scenarios. It is important to discuss biomarker testing with the oncology team because it helps identify who might benefit most from these therapies. For patients whose tumors carry PD-L1 expression, immunotherapy plus chemotherapy may be considered in the frontline setting.
