Triple-Negative Breast Cancer (TNBC)

April 10, 2025

This page was reviewed under our medical and editorial policy by Hannah Chang, M.D., assistant professor, and Susan Yost, Ph.D., staff scientist, Department of Medical Oncology & Therapeutics Research, City of Hope^® Cancer Center Duarte

Triple-negative breast cancer (TNBC) is an uncommon and aggressive form of invasive breast cancer, accounting for about 10% to 15% of all breast cancers. Because treatment options for this cancer are limited, it is more challenging to treat compared to other breast cancers.

What Is TNBC?

With breast cancer, three types of receptors on the surface of the cancer cells may help cancer thrive. These receptors are:

• Estrogen, a female hormone
• Progesterone, a female hormone
• Human epidermal growth factor receptor 2 (HER2), a protein

When these receptors are present, medications and other treatments are available to help block the cells from using these hormones and proteins to grow.

In triple-negative breast cancer, none of these receptors is present. This limits the available treatment options. Fewer treatment options mean the prognosis of TNBC is poorer than other forms of breast cancer.

Is It an Aggressive Form?

Aggressive cancer is a tumor or disease that develops quickly and grows or spreads faster than other forms. TNBC falls in this category. As an invasive type of breast cancer, TNBC is likely to spread beyond the site where it begins in the breast. There is also a high risk for TNBC to spread beyond the breast. TNBC is the most aggressive form of breast cancer.

TNBC Symptoms

The signs and symptoms of triple-negative breast cancer are similar to those of other forms of breast cancer:

• Pain in the breast or nipple
• Swollen lymph nodes in the armpit (axilla) or under the collarbone
• Liquid (other than breast milk) or blood coming from the nipple
• A nipple that turns inward or flattens
• Lump in the breast
• Changes to the skin of the breast

TNBC Skin Symptoms

Skin changes with TNBC may indicate inflammatory breast cancer (IBC). IBC is rare but very aggressive.

Inflammatory TNBC is an especially aggressive subtype of TNBC. Skin changes to the breast with this form of TNBC are caused by the cancer cells blocking lymph vessels in the skin of the breast. This causes the lymph fluid to build up under the skin and change the appearance of the breast. The skin of the breast may have the following symptoms, which may be called a breast cancer rash:

• Dimpling or pitting of the skin that may give an appearance similar to the skin of an orange, called peau d’orange
• Swelling (edema) and redness affecting at least one-third of the breast
• Pink, purple or bruised appearance

Patients with symptoms should follow up with their primary care provider, who will perform an exam and tests to assess for breast cancer and, if found, determine the type and treatment options. This evaluation may include:

• A physical exam to check for lumps or masses in the breasts, swollen lymph nodes or skin changes
• Imaging of the breasts, such as mammogram, breast ultrasound or magnetic resonance imaging (breast MRI)
• A biopsy of breast tissue
• Genetic testing

What Causes Triple-Negative Breast Cancer?

Breast cancer is triggered by changes in cells of the breast that hold genetic information, known as DNA (deoxyribonucleic acid). Most studies attribute the changes to a combination of factors.

Risk factors for breast cancer may include:

• Older age
• Dense breast tissue
• Early menstruation
• Giving birth at an older age or never done so
• Later menopause
• Obesity
• Alcohol use
• A history of radiation therapy to the breast or chest
• Mutations to BRCA1 or BRCA2 genes

TNBC is more common in women:

• Under age 40 who have not entered menopause
• Whose ethnicity is Black or Hispanic
• With the BRCA1 genetic mutation
• Of Ashkenazi Jewish descent

TNBC Treatment

Fewer treatment options for TNBC are available due to the absence of the hormone and protein cell receptors.

Commonly used hormone therapy and drugs that target HER2 proteins are not useful. Often, surgery to remove the tumor and some or all of the breast is the first treatment, followed by radiation therapy or chemotherapy to destroy any remaining cancer cells.

Lumpectomy: This surgery removes the primary tumor from the affected breast. Healthy tissue around the tumor and part of the chest wall may be removed as well. Lymph nodes around the breast are usually removed at the same time to determine if the cancer is spreading. Surgery typically takes one to two hours, and most patients go home the same day.

Mastectomy: This surgery removes all or part of the breast along with nearby lymph nodes. Some patients may have reconstructive breast surgery at the same time or months later.

Radiation therapy for breast cancer: This treatment uses high-energy radiation to destroy cancer cells and shrink tumors. Radiation therapy follows a lumpectomy to destroy any remaining cancer cells. External beam radiation therapy (EBRT), the most common form, uses a machine outside the body to focus a beam of radiation at the cancer. Brachytherapy uses radiation internally. A device containing small pellets or seeds is temporarily placed near the site where cancer was removed.

Breast cancer chemotherapy: The primary full body (systemic) treatment for TNBC, chemotherapy uses medications to destroy cancer cells. Chemotherapy may be given by injection, through intravenous (IV) infusion or by mouth. TNBC responds well to chemotherapy, but it tends to return more frequently than other breast cancers.

Triple-Negative Breast Cancer Survival Rate

Survival rates are drawn from the percentage of people who were still living five years or more after their cancer diagnosis. Each person’s case and survival rate will differ. These estimates provide information on the potential for treatment success.

The National Cancer Institute Surveillance, Epidemiology, and End Results Program (SEER) database tracks five-year relative survival rates based on cancer spread.

Localized (cancer confined to the breast): 91%.

Regional (cancer has spread to nearby areas): 66%.

Distant (cancer has spread to distant areas such as the bones or lungs): 12%.

The SEER numbers are based on cancer stage at diagnosis and do not account for advances in cancer treatment. They are not predictive of any individual patient’s outcome. As with other forms of breast cancer, early detection with routine screening may help improve a patient’s prognosis.