Triple-negative breast cancer (TNBC) is a rare type of breast cancer. It is harder to treat and much more aggressive.

Because it is rare and more aggressive than other types of breast cancer, there are fewer treatment options available for TNBC. It also tends to have a higher rate of recurrence.

This form of cancer accounts for around 10–15% of all breast cancer diagnoses.

In this article, we look at the risk factors, diagnosis, and available treatments for triple-negative breast cancer.

The term triple-negative breast cancer means that cancer cells do not have estrogen or progesterone receptors and do not produce large amounts of human epidermal growth factor receptor 2 (HER2).

When diagnosing cancer types, doctors will test for the presence of these receptors and protein production. If all three tests return negative results, a person has triple-negative breast cancer.

Other types of breast cancer include:

  • estrogen receptor-positive (ER-positive)
  • progesterone receptor-positive (PR-positive)
  • HER2 receptor-positive

If cancer cells are positive for either ER or PR-positive receptors, doctors can target the cancer with hormonal treatments. HER2 receptor-positive cancer is treated with anti-her2-based treatments.

However, no targeted therapies are available for TNBC. It is also more likely than other types of breast cancer to spread and recur.

The symptoms of TNBC are similar to the symptoms of most types of breast cancer. Typically a person would notice a lump or a mass on their breast, though most lumps and breast changes do not turn out to be cancer.

Other symptoms a person may experience include:

  • swelling or unusual dimples on the breasts
  • breast or nipple pain
  • nipple turning inward
  • redness, dryness, and flakiness on the skin of the breast
  • nipple discharge that isn’t lactation
  • swollen lymph nodes

In People of Color, there may be less visible redness on the breast, but the other symptoms would be the same.

There are fewer treatment options for TNBC than for other types of breast cancer. Hormone therapies are not effective against TNBC, since it lacks estrogen and progesterone receptors.

However, several different treatments are available, and researchers are looking for additional medications to help treat and prevent this aggressive cancer.

Currently, treatment options for TNBC include:

Surgical options include the partial (lumpectomy) or full (mastectomy) removal of one or both breasts.

An important part of any treatment plan is remaining active and eating a variety of healthful foods. The side effects of cancer treatment can be difficult to manage, so maintaining a balanced diet with few processed foods, getting regular exercise, and resting can help improve how a person manages the adverse effects.

Find out all about chemotherapy here.

Researchers have not determined definitively what causes TNBC, but there may be a link to mutations in the BRCA1 gene in some cases.

Studies show that 69% of women with an inherited BRCA1 mutation who develop breast cancer have this type of breast cancer. That said, only about 10–15% of people with TNBC have this mutation.

However, not everyone who carries this gene gets cancer, and people without it can also get TNBC, so more research on this is necessary.

Researchers have identified the following risk factors for developing TNBC over other types.

  • Obesity and inactivity: Studies suggest that people with obesity and a higher body mass index (BMI) have a higher chance of developing triple-negative breast cancer. These categories tend to include those who are not very active.
  • Genetics: A 2018 study identified several genes associated with a high risk of triple-negative breast cancer. In particular, around 70% of breast cancers in people with a BRCA gene mutation are triple-negative.
  • Age: Individuals under 50 years of age have a higher risk of developing triple-negative breast cancer.
  • Race: African American and Hispanic women are more susceptible to triple-negative breast cancer.
  • Pregnancy: Research has found that after pregnancy, women may have more of a chance of getting triple-negative breast cancer.

As with other types of breast cancer, a person may feel a small, hard bump on or near their breast. In other cases, a routine scan of the breasts may reveal an area of concern.

To diagnose breast cancer, doctors use the following tests:

  • Mammogram: This is an x-ray of the breast, which is an annual screening recommended for females assigned at birth (FAAB) starting at age 45. Those between the ages of 40–44 can choose to start annual mammograms, according to the American Cancer Society.
  • Ultrasound: This may be a better choice than a mammogram for people with denser breast tissue, or a doctor may want to get a closer look at something they saw on a mammogram.
  • MRI: This is used along with a mammogram for people with a higher risk of developing breast cancer or to check the extent of a known cancer.

These are the most common tests used to diagnose breast cancer, though there are other, newer assessment methods.

Upon the detection of growth, the doctor will collect tissue samples for assessment as part of a biopsy. The result of this will highlight the type of breast cancer. A person whose cancer tests negative for the estrogen, progesterone, and HER2 receptors will receive a diagnosis of TNBC.

A doctor will then assign a stage to the cancer based on the findings of the biopsy and any follow-up scans. They calculate the stage based on tumor size and the spread, if any, of the cancer.

Here, learn more about how a biopsy works.

While there’s no guaranteed way to prevent someone from developing breast cancer, a person can try to influence some of the risk factors for the disease. For example, they can:

  • maintain a healthy weight
  • exercise regularly
  • avoid or limit alcohol and smoking
  • eat a balanced diet and make sure to supplement any vitamins or minerals if needed

In addition, it is a good idea to avoid or limit exposure to carcinogenic chemicals or medications that are associated with breast cancer. This includes chemicals such as polychlorinated biphenyl (PCB) and dichlorodiphenyltrichloroethane (DDT), and medications like antibiotics, statins, and blood pressure medications.

Depending on their health, a person may need to take some of these medications at some in their lives, so they should consult their doctor as to how much to take and for how long.

In addition, a person should avoid diethylstilbestrol, a nonsteroidal estrogen medication with a high association with breast cancer in FAABs. That said, it is currently rarely used.

Researchers describe the outlook for cancer in 5-year survival rates.

Doctors may define a person’s cancer as:

  • Local: Cancer cells are present at a single site in the breast.
  • Regional: Cancer cells spread to other tissues within the breast.
  • Distant: Cancer cells have spread to other organs, glands, or tissues.

The American Cancer Society estimates relative 5-year survival rates to be:

Cancer stage at diagnosisRelative 5-year survival rate
all stages combined77%

However, many factors can affect a person’s outlook following treatment, including:

  • when they discovered the cancer and started receiving medical treatment for it
  • the stage of the cancer and whether it has spread to other tissues and organs
  • how the cancer responds to treatment

How bad is triple-negative breast cancer?

The prognosis for TNBC is worse than for other types of breast cancer, but the overall prognosis depends on the stage of the cancer at diagnosis.

Catching cancer in its earliest stages and undergoing effective treatment may help improve the prognosis.

Can you fully recover from triple-negative breast cancer?

A 2019 study showed that 40% of people with stages 1–3 of TNBC will experience a recurrence after treatment.

However, this also means that 60% of people are able to remain healthy long-term.

There are many things to consider after a diagnosis of TNBC, and it’s common to have many questions.

A person should begin by reading about this type of cancer and finding a doctor who specializes in it.

Depending on whether a person’s cancer has metastasized or not, they may be headed for different degrees of treatment. They may need to have surgery and may experience side effects from things like chemotherapy or radiation.

The TNBC Foundation offers additional information about resources and support.

Triple-negative breast cancer (TNBC) is a rare and aggressive form of breast cancer.

Its rarity means fewer treatment options are available compared to other types, and it tends to have a higher rate of returning after treatment. This makes it difficult to treat.

However, there are treatments available, as well as new medications that show promise.