Triple-negative breast cancer (TNBC) is a fast-growing cancer that requires aggressive treatment. The term “triple-negative” means that the breast cancer cells don’t contain three proteins found in different types of breast cancer.

About 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 triple-negative. The journal Cancer Epidemiology, Biomarkers & Prevention reports that women who are younger than 40, Black, or Hispanic have a higher risk of developing TNBC.

1. What Sets TNBC Apart From Other Breast Cancers?

Doctors may categorize breast cancer by subtype based on the proteins 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:

• 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 the body produces. 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. This prevents cancer cells from growing and eventually kills the cells.

When a person’s breast cancer cells don’t contain any of these three proteins, doctors refer to it as “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.

2. What Are the Risk Factors for TNBC?

TNBC tends to affect women at younger ages than other types of breast cancer. Among all types of female breast cancer, women are diagnosed at an median age of 63, according to the National Cancer Institute. A 2018 study in Cancer Treatment and Research Communications found that, among women with TNBC in the United States, the average age is 54.1.

Some gene changes, such as mutations in the BRCA genes, can also lead to a high risk of breast cancer. These gene changes are passed down from parent to child. If you have a family history of breast or ovarian cancer, there is a chance you may have a BRCA mutation. Ask your doctor about genetic testing for these genes.

Racial and Ethnic Risk Factors

According to the American Cancer Society, both Black and Hispanic women are more likely to be diagnosed with TNBC than non-Hispanic white women. TNBC makes up 20 percent of breast cancer cases in Black women compared to 10 percent of cases in the general population. This group also has a higher chance of diagnosis at a younger age and at a more severe cancer stage. Genetic and socioeconomic factors likely play a role in the racial disparities (inequalities) for TNBC, but more research is needed to fully understand this heightened risk.

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

3. What Are the Symptoms of TNBC?

TNBC causes similar symptoms as other forms of breast cancer. These may include:

• A hard lump in the breast or armpit
• Swelling of the breast
• Skin changes, such as discoloration, dimpling, or creases
• An inverted nipple
• Nipple discharge in one breast
• Changes in breast appearance
• Breast pain

Several other health conditions besides cancer can cause these symptoms. In addition, many people who are diagnosed with breast cancer don’t have any symptoms at all. Follow your doctor’s advice when it comes to getting screened for breast cancer, and tell your doctor if one or both breasts start looking or feeling different than normal.

4. How Do Doctors Diagnose TNBC?

Breast cancer diagnosis often starts when a person or their doctor notices a lump in the breast, or when a screening test for breast cancer detects unusual breast tissue. After finding a mass, the doctor will perform additional imaging tests, as well as a biopsy.

Several types of imaging tests can capture pictures of the inside of the breast, helping the doctor see whether there are any problems. Imaging tests may include a mammogram, ultrasound, or MRI. An MRI can also help doctors prepare for surgery or, when used with other tests, figure out if cancer has spread to different parts of the body.

A biopsy is the only test that can officially diagnose breast cancer. During this test, the doctor uses a needle to remove a small sample of tissue. The tissue is sent to a laboratory, where a pathologist runs tests to determine whether the cells in the sample are cancerous. Laboratory tests can also identify the cancer’s type, molecular subtype, and grade (how abnormal the cancer cells look and how fast they are growing). Doctors use this information to estimate a person’s prognosis (outlook) and know which treatments are likely to work best.

Stages of Triple-Negative Breast Cancer

During the process of diagnosis, doctors will also assign a cancer stage. The stage tells you how far the cancer has spread within the body. Early-stage tumors located in one small spot are stages 0 to 1. Advanced TNBC that has metastasized (spread to distant organs or tissues) is described as stage 4. Stages are sometimes represented using Roman numerals, such as stage IV, for example.

5. How Is TNBC Treated?

Treatments for TNBC may include 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).

Chemotherapy is often the main treatment given to people with breast cancer, sometimes in combination with an immunotherapy drug such as pembrolizumab (Keytruda). Chemotherapy may be given at different points along the treatment journey. Neoadjuvant therapy is given before surgery to shrink a tumor and make it easier to remove. Adjuvant therapy is given after surgery to remove any remaining cancer cells left behind.

Targeted treatments such as olaparib (Lynparza) or talazoparib (Talzenna) may be recommended for people with BRCA mutations. People with metastatic TNBC who have already tried other treatments may be able to receive the immunotherapy sacituzumab govitecan-hziy (Trodelvy).

Triple-negative breast cancer treatment may also involve surgery, such as a lumpectomy, mastectomy, or a procedure to remove one or more axillary lymph nodes.

After surgery, the doctor may recommend 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 lack this gene, they are less likely to be able to repair damage and survive.

6. What Are the Chances of Survival?

TNBC often leads to a poor prognosis . This type of cancer can be hard to treat. TNBC is more likely to be an invasive breast cancer that metastasizes. It’s also more likely to relapse than other types of cancer. Nonetheless, treatment options are always improving, and every person’s situation is unique.

The American Cancer Society reports that overall, women 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, according to the American Cancer Society:

• Women 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.
• Women with TNBC that has begun to grow into surrounding tissues are 66 percent as likely to live at least five years.
• Women with metastatic TNBC, who have had cancer cells spread to other areas outside the breast and chest, are 12 percent as likely to live at least five years, compared to others without TNBC.

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

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 are interested in learning more about your prognosis, talk to your health care team. Your doctor can explain how your individual factors affect your outlook and help you understand what to expect from your cancer care plan. If you want more treatment options, ask your oncologist about clinical trials you may be eligible to join.

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.

Have you or a family member been diagnosed with TNBC? What treatment options have you tried for your breast cancer? Share your experiences in the comments below, or start a conversation by posting on your Activities page.