Triple-negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive type of invasive breast cancer. TNBC differs from other types of invasive breast cancer in that it tends to grow and spread faster, has fewer treatment options, and tends to have a worse prognosis (outlook).

The term triple-negative breast cancer refers to the fact that the cancer cells don’t have estrogen or progesterone receptors (ER or PR) and also don’t make any or too much of the protein called HER2. (The cells test "negative" on all 3 tests.)

How common is triple-negative breast cancer?  

Triple-negative breast cancer accounts for about 10-15% of all breast cancers. These cancers tend to be more common in women younger than age 40, who are Black, or who have a BRCA1 mutation.

Signs and symptoms of triple-negative breast cancer

Triple-negative breast cancer can have the same signs and symptoms as other common types of breast cancer.

How is triple-negative breast cancer diagnosed?

Once a breast cancer diagnosis has been made using imaging tests and a biopsy, the cancer cells will be checked for certain proteins. If the cells do not have estrogen or progesterone receptors (ER or PR), and also do not make any or too much of the HER2 protein, the cancer is considered to be triple-negative breast cancer.

Survival rates for triple-negative breast cancer

TNBC tends to grow quickly, is more likely to have spread at the time it’s found, and is more likely to come back after treatment than other types of breast cancer. Because of this, the survival rates for TNBC are generally not quite as high as they are for other types of breast cancer.

Survival rates can give you an idea of what percentage of people with the same type and stage of cancer are still alive a certain amount of time (usually 5 years) after they were diagnosed. They can’t tell you how long you will live, but they may help give you a better understanding of how likely it is that your treatment will be successful.

Keep in mind that survival rates are estimates and are often based on previous outcomes of large numbers of people who had a specific cancer, but they can’t predict what will happen in any particular person’s case. These statistics can be confusing and may lead you to have more questions. Talk with your doctor about how these numbers may apply to you, as they are familiar with your situation.

What is a 5-year relative survival rate?

A relative survival rate compares women with the same type and stage of breast cancer to women in the overall population. For example, if the 5-year relative survival rate for a specific stage of breast cancer is 90%, it means that women who have that cancer are, on average, about 90% as likely as women who don’t have that cancer to live for at least 5 years after being diagnosed.

Where do these numbers come from?

The American Cancer Society relies on information from the Surveillance, Epidemiology, and End Results Program (SEER) database, maintained by the National Cancer Institute (NCI), to provide survival statistics for different types of cancer.

The SEER database tracks 5-year relative survival rates for breast cancer in the United States, based on how far the cancer has spread. The SEER database, however, does not group cancers by AJCC TNM stages (stage 1, stage 2, stage 3, etc.). Instead, it groups cancers into localized, regional, and distant stages:

• Localized: There is no sign that the cancer has spread outside of the breast.
• Regional: The cancer has spread outside the breast to nearby structures or lymph nodes.
• Distant: The cancer has spread to distant parts of the body such as the lungs, liver, or bones.

5-year relative survival rates for triple-negative breast cancer

These numbers are based on women diagnosed with TNBC between 2012 and 2018.

SEER Stage	5-year Relative Survival Rate
Localized	91%
Regional	66%
Distant	12%
All stages combined	77%

Understanding the numbers

• Women now being diagnosed with TNBC may have a better outlook than these numbers show. Treatments improve over time, and these numbers are based on women who were diagnosed and treated at least 5 years earlier.
• These numbers apply only to the stage of the cancer when it is first diagnosed. They do not apply later on if the cancer grows, spreads, or comes back after treatment.
• These numbers don’t take everything into account. Survival rates are grouped based on how far the cancer has spread, but your age and overall health, how well the cancer responds to treatment, tumor grade, and other factors can also affect your outlook.

Treating triple-negative breast cancer

Triple-negative breast cancer has fewer treatment options than other types of invasive breast cancer. This is because the cancer cells do not have the estrogen or progesterone receptors or enough of the HER2 protein to make hormone therapy or targeted HER2 drugs work. Because hormone therapy and anti-HER2 drugs are not choices for women with triple-negative breast cancer, chemotherapy is often used.

If the cancer has not spread to distant sites, surgery is an option. Chemotherapy might be given first to shrink a large tumor, followed by surgery. Chemotherapy is often recommended after surgery to reduce the chances of the cancer coming back. Radiation might also be an option depending on certain features of the tumor and the type of surgery you had.

In cases where the cancer has spread to other parts of the body (stage IV), platinum chemotherapy, targeted drugs like a PARP inhibitor or antibody-drug conjugate, or immunotherapy with chemotherapy might be considered.

For details, see Treatment of Triple-negative Breast Cancer.