Triple-negative breast cancer (TNBC) grows quickly and needs strong treatment. The term “triple-negative” means that the breast cancer cells test negative for estrogen receptors, progesterone receptors, and the protein HER2, which are common features in other types of breast cancer.

Almost 200,000 people are diagnosed with TNBC throughout the world each year. Out of all breast cancer cases, around 10 percent to 15 percent are the triple-negative type. Women who are younger than 40, Black, or Hispanic have a higher risk of developing TNBC.

What Is Triple-Negative Breast Cancer?

Before diving into treatment options, it’s important to understand TNBC on a deeper level. There are several ways in which breast cancer can be classified. One way of describing the type of breast cancer is by identifying which cell type originally became cancerous and whether the cancer is invasive (has spread to other areas). Using these criteria, breast cancer may be called “ductal carcinoma in situ” (noninvasive) or “invasive lobular carcinoma.”

Another way that doctors categorize breast cancer is by the molecular subtype. The molecular subtype refers to proteins that are found inside or on the outside of cancer cells. These proteins receive messages from other parts of the body and tell the cell when to grow and what to do. There are three main proteins that doctors look for when determining the molecular subtype:

• Estrogen receptor (ER)
• Progesterone receptor (PR)
• Human epidermal growth factor receptor 2 (HER2)

ER and PR are types of proteins called hormone receptors. These proteins attach to hormones (molecules that act as signals) that are produced by the body. Breast cancer cells that contain ER or PR rely on hormones to continue growing. Likewise, breast cancer cells that have HER2 on their surface rely on HER2 to grow.

Doctors use the terms “positive” and “negative” to describe a cancer’s status. For example, breast cancer that is hormone receptor-positive contains one or both of the hormone receptor proteins. Researchers have developed drug treatments that can block ER, PR, and HER2. These treatments prevent cancer cells from growing and eventually kill the cells.

When a person’s breast cancer cells don’t contain any of these three proteins, doctors say that the cancer is triple-negative. Because TNBC cells don’t rely on ER, PR, or HER2 to grow, they don’t respond to drugs that block these proteins. This means that TNBC is harder to treat than other types of breast cancer.

Treatment of Triple-Negative Breast Cancer

TNBC is often treated with chemotherapy, surgery, radiation therapy, or a combination of these options. A person’s treatment plan may be different depending on their disease stage and whether the cancer has relapsed (come back after being treated).

Other types of breast cancer are often treated with targeted therapies and hormone therapies. These drugs block the proteins ER, PR, and HER2. Because TNBC doesn’t contain these proteins, many targeted therapies and hormone therapies will not work.

1. Chemotherapy

Most people with TNBC take chemotherapy drugs to help kill cancer cells. Chemotherapy may be given at different points along the treatment journey:

• Neoadjuvant therapy — Treatment received before surgery, to shrink a tumor and make it easier to remove
• Adjuvant therapy — Treatment received after surgery, to remove any remaining cancer cells left behind

Many types of chemotherapy drugs are given to people with breast cancer, including TNBC. Platinum-based drugs, including cisplatin (Platinol) and carboplatin (Paraplatin), prevent cancer cells from repairing themselves. These drugs allow damage to build up until the cancer cell dies. Taxane drugs like docetaxel (Taxotere) and paclitaxel protein-bound (Abraxane) prevent cells from growing and dividing. Anthracycline drugs also stop cells from dividing and create damage within a cell. Capecitabine (Xeloda) slows down cancer cell growth. These chemotherapy drugs and others are often given together in different combinations.

2. Targeted Therapy and Immunotherapy

Targeted therapy or immunotherapy drugs may be available for people with certain gene mutations (changes) or for those who have been diagnosed with advanced TNBC.

People with changes in BRCA genes may be able to take drugs called poly (ADP-ribose) polymerase (PARP) inhibitors, including talazoparib (Talzenna) or olaparib (Lynparza). If a person’s cancer cells make a protein called PD-L1, they may be able to take the immunotherapy drug pembrolizumab (Keytruda). People with metastatic disease who have already tried other treatments may be able to receive the antibody-drug conjugate sacituzumab govitecan-hziy (Trodelvy), another type of immunotherapy.

3. Surgery

Many people with TNBC undergo surgery to remove the breast cancer, although this may not be an option for those with stage 4 metastatic cancer. If the tumor is small and located in just one part of the breast, lumpectomy may be an option. During a lumpectomy, doctors remove cancer cells and a small amount of surrounding healthy breast tissue. If the tumor is larger or has spread further throughout the breast, surgeons may need to perform a mastectomy, in which all of the breast tissue is taken out.

In many cases, people with TNBC will need surgery to remove one or more lymph nodes. Lymph nodes are small structures that help filter out waste and foreign particles from the body. When a tumor develops, cancer cells often collect in nearby lymph nodes. Surgically removing the lymph nodes helps doctors see whether cancer cells have begun to spread, which helps them determine staging and make treatment decisions.

If one, two, or three lymph nodes are taken out, the procedure is called a sentinel lymph node biopsy. When doctors remove many lymph nodes, the surgery is called an axillary lymph node dissection.

4. Radiation Therapy

After surgery, some people with TNBC receive radiation therapy, in which high-energy particles or beams are directed at the breast and surrounding area. Radiation treatments can help damage and kill any surviving breast cancer cells. This may be especially helpful for people with BRCA1 mutations. When cancer cells don’t have this gene, they are less likely to be able to repair damage and survive.

5. Clinical Trials

Researchers have been looking for other possible treatment options for TNBC. They have identified additional gene changes that often occur in TNBC cells, and they’re looking for other drugs that may be able to target these gene changes.

Researchers study whether new drugs are safe and effective and test new drug doses and treatment plans using clinical trials. People with TNBC might have the chance to try out new treatment options by participating in clinical trials.

Read more about how to make sure you get access to the best TNBC treatment, specially tailored for diverse needs, including helpful information for women of color.

Common Treatment Side Effects

Your side effects will depend on your health status, medical history, and which combination of treatments you receive.

Side effects from chemotherapy usually include nausea (within a day or two of treatment) and hair loss (within two to four weeks of starting treatment). Your doctor may be able to prescribe medication to help with nausea and offer suggestions to minimize hair loss. It’s normal to feel tired and have trouble concentrating in the weeks after chemo and radiation treatments.

Radiation can cause changes to skin color and texture, similar to a sunburn.

If you have lymph nodes removed during surgery, you may develop a type of swelling called lymphedema.

Side effects of targeted and immunotherapy vary from drug to drug and may depend on whether they’re combined with other treatments.

Always discuss side effects with your health care provider for guidance on how to manage them.

Triple-Negative Breast Cancer Prognosis

TNBC often leads to a poor prognosis (outlook). This type of cancer is often hard to treat. TNBC is more likely to metastasize (spread) and relapse.

The American Cancer Society notes that people with TNBC are 77 percent as likely to live for at least five years after they are diagnosed compared to people without the disease. However, survival rates vary widely based on the breast cancer stage:

• People with TNBC that is only growing within one small area are 91 percent as likely to live for five years or more once they receive their diagnosis.
• People with TNBC that has begun to grow into surrounding tissues are 66 percent as likely to live at least five years.
• People with metastatic TNBC, where cancer cells have spread to areas outside the breast and chest, are 12 percent as likely to live at least five years compared to those without TNBC.

Breast cancer survival rates are constantly improving as researchers develop better treatments. The above survival rates were calculated using data from people diagnosed with breast cancer between 2012 and 2018. People being diagnosed today may have better survival rates.

Various factors also play a role in outlook. People at least 65 years old are more likely to have a poor outcome from TNBC. Additional elements that may lead to a worse prognosis include having other health conditions, a higher tumor grade, or finding cancer cells in the lymph nodes. Factors that may lead to a better outcome for people with TNBC include high levels of platelets and low levels of CA15-3 (a protein made by breast cancer cells).

If you want to learn more about your prognosis, talk to your health care team. Your doctor can explain how your factors affect your outlook and help you understand what to expect.

Talk With Others Who Understand

MyBCTeam is the social network for people with breast cancer and their loved ones. On MyBCTeam, more than 67,000 members come together to ask questions, give advice, and share their stories with others who understand life with breast cancer.

Are you living with triple-negative breast cancer? Share your experience in the comments below, or start a conversation by posting on your Activities page.