What Is Triple-Negative Breast Cancer?

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Triple-negative breast cancer (TNBC) is a type of breast cancer that does not have hormone receptors. TNBC is diagnosed in 10% to 15% of all cases of breast cancer. Due to the lack of hormone receptors, there are limited treatment options. However, there are still treatments available, and the prognosis is good when caught early.

This article will discuss TNBC symptoms, diagnosis, and treatment. It will also cover TNBC staging and outlook.

A healthcare provider talks to a person in mammogram imaging room

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Triple-Negative Breast Cancer: What Does It Mean?

TNBC is a type of breast cancer that does not have estrogen or progesterone receptors and does not make any or much of the human epidermal growth factor receptor 2 (HER2). Since TNBC tests negative on these three tests, it is called triple-negative breast cancer.

Having breast cancer that has HER2, estrogen, or progesterone receptors increases your available treatment options. Hormone therapy and medications can be prescribed for people who test positive for these three factors.

Having breast cancer without these receptors decreases your treatment options. However, though treatments are limited, there are still successful treatments available for TNBC.

Understanding TNBC Prognosis: Influencing Factors

TNBC prognosis is determined for an individual based on factors that include the characteristics of their tumor, the stage at diagnosis, age, their overall health, other conditions they have, and what treatments are recommended for them.

A survival rate cannot tell an individual how long they will live after their cancer diagnosis, but it provides a picture of the success of cancer treatment for that specific type and stage of cancer.

A survival rate is based on the outcomes of people who have the same cancer and are diagnosed with the same stage of cancer as you. It gives you the percentage of those people who are still alive after a designated amount of time after their diagnosis.

Similar to the survival rate is a relative survival rate. This looks at people with the same type and stage of cancer and people in the general population.

The National Cancer Institute (NCI) keeps a database that provides survival statistics for different types of cancer. The five-year relative survival rates for TNBC for people diagnosed between 2012 and 2018 are:

  • Localized: 91%
  • Regional: 66%
  • Distant: 12%
  • All stages combined: 77%

It's important to note that these relative survival rates are from people who had TNBC five years ago or longer. Treatments are constantly changing and survival rates can also change over time. Another key item to note is that these survival rates are only reflective of people when they have first been diagnosed. It does not take into account cancer that worsens or has gone away and comes back.

Triple-Negative Breast Cancer Symptoms

Symptoms of TNBC are similar to symptoms of other types of breast cancer. There can be several symptoms or none at all. The most common symptom is a lump or mass in a breast. Other symptoms include:

  • Lump or hard mass in a breast
  • Redness, swelling, warmth, or pitting (orange peel texture) on a breast
  • Breast pain
  • Breast size or shape changes
  • Fluid discharge from a nipple
  • Nipple skin peeling or flaking

What Causes Triple-Negative Breast Cancer?

The causes of TNBC are likely linked to mutations of the BRCA1 gene. A 2022 study found that 85% of people with breast cancer who had a BRCA1 gene mutation had TNBC.

The BRCA1 gene protects the body from cancer development. When this gene does not work properly, it can lead to other genetic changes that have been linked to breast and ovarian cancer.

Many risk factors have been associated with TNBC. These risk factors can increase the likelihood that someone develops TNBC, but they do not cause the condition. Factors include:

  • Age: Breast cancer tends to occur in people over 60, but TNBC is more commonly seen in younger people who are under 50.
  • Sex: Females are more likely than males to develop TNBC (when citing research, the terms for sex and gender from the sources are used)
  • Family history: People who have a family history of breast cancer have a higher risk of developing the condition.

In the United States, Blacks and Hispanics are more likely to be diagnosed with TNBC than Asians and Whites. The reasons for this are not clear.

What Does TNBC Use for Food and Fuel?

Researchers are looking for what feeds or fuels TNBC since it lacks the receptors for hormones that drive the growth of some other forms of breast cancer.

One study on mice models of TNBC found that limiting the amino acid asparagine (present in asparagus and some other foods) in the diet and by other means can reduce the likelihood of distant spread in TNBC. However, results from animal experiments do not always apply to humans.

Testing to Diagnose Triple-Negative Breast Cancer

Testing to diagnose TNBC is similar to that of other types of breast cancers. After a breast lump has been found, a healthcare provider will order additional testing. This can include a mammogram, ultrasound, or breast magnetic resonance imaging (MRI).

If indicated, a healthcare provider will perform a biopsy. In this procedure, a sample of the breast tissue is removed and its cells are analyzed in a lab.

If the biopsy comes back positive for breast cancer, then additional testing will be done to look at the cell receptors to determine if the cancer is TNBC. If the hormone testing and HER2 blood test come back negative, then the cancer is TNBC.

Genetic Testing for Triple-Negative Breast Cancer

The current recommendations by the National Comprehensive Cancer Network (NCCN) are that people who have an increased risk of breast cancer be tested for mutations to the BRCA1 and BRCA2 genes. 

Genetic testing does not diagnose TNBC or other breast cancer. It provides a better look at a person's risk of developing breast cancer. This information can aid the person and healthcare providers in making decisions about their health and future breast cancer screenings.

Triple-Negative Breast Cancer Staging

TNBC and other types of breast cancer are staged in the same way. They use a number scale from 0 to 4. The higher the number, the more advanced the cancer is.

Stage 0

The first stage of TNBC indicates that the cancer cells have not spread. The cancer cells are within the breast lobes or milk ducts.

Stage 1

Stage 1 TNBC is when the cancer cells have spread but only to one lymph node that is nearby the breast.

Stage 2

Stage 2 breast cancer are those that are moderate in size and remain in the lymph nodes and underarm area.

Stage 3

TNBC has been identified as stage 3 is advanced and has spread past the breast but cancer cells have not been found in other organs.

Stage 4

Stage 4 TNBC is the most advanced breast cancer stage and shows that cancer has spread to other organs within the body.

How and Where Does TNBC Spread?

TNBC can spread to distant areas of the body like the liver, lungs, and brain. It starts when the cancer cells break off from the original tumor. These cells then move to the blood vessels or lymph nodes. From there they travel through the blood or the lymphatic fluid to other areas of the body.

Triple-Negative Breast Cancer Treatment

TNBC is treated differently than other types of cancer. Since there are no hormone receptors, certain medications are not effective treatments. Therefore, healthcare providers primarily use chemotherapy, radiation, and surgery to treat TNBC.


Chemotherapy for TNBC can be done before or after surgery, or at both times. When chemotherapy is done before surgery, it is used to shrink the tumor to make it easier to remove. Chemotherapy used after surgery is used to get rid of any cancer cells that have spread throughout the body.

Chemotherapy decreases the likelihood that cancer will return.


After the TNBC tumor has been removed, radiation treatment begins. This procedure takes about 20 minutes each day and is performed for four to five days a week for six weeks. It uses radiation to focus on the breast to eliminate any cancer cells that may remain.


Surgery is used to remove the breast cancer lump (lumpectomy) or to remove the entire breast (mastectomy). A lumpectomy will also remove any nearby lymph nodes to see if cancer has spread. This procedure is typically done on an outpatient basis.

A mastectomy removes all of the breast tissue and nearby lymph nodes. It is a much more invasive procedure.

New Treatments for TNBC

TNBC treatments are evolving as researchers learn more about the condition. The latest advancements in TNBC treatment include:

  • Immunotherapy: Immunotherapy has been shown to be a new and effective treatment for TNBC. The Food and Drug Administration (FDA) has approved two types, Tecentriq (atezolizumab) and Keytruda (pembrolizumab), for TNBC treatment.
  • Poly-ADP ribose polymerase (PARP) inhibitors: This class of medications can contribute to cell death in BRCA-mutated tumor cells. Examples are Lynparza (olaparib), Talzenna (talazoparib), and veliparib.
  • PI3K inhibitors: An example of this class of medications is buparlisib, although its manufacturer, Novartis, has ended clinical trials for treating breast cancer with this drug.

Treatments are continuously being developed and tried in clinical trials. Many times, a combination of treatments are most effective.

TNBC Treatment Side Effects

TNBC treatment will have side effects. These side effects will vary from person to person but can include:

Outlook for Triple-Negative Breast Cancer

TNBC can be a difficult type of breast cancer to treat due to the lack of hormone receptors. This type of cancer grows more quickly and has a higher rate of recurrence than other breast cancers. However, a prompt diagnosis and treatment can be successful and have an overall five-year survival of 77%.

Living With TNBC: Support and Resources

Anyone who has been diagnosed with TNBC will need a support system. This can include family and friends or a social worker who guides the patient to community support and resources.

Don't hesitate to reach out to find resources in the area that support people with breast cancer. If someone is unfamiliar with the resources available, talk to a healthcare provider, social worker, or local support group.

12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Patty Weasler, RN, BSN
Patty is a registered nurse with over a decade of experience in pediatric critical care. Her passion is writing health and wellness content that anyone can understand and use.