Triple-negative breast cancer (TNBC) cells do not have estrogen or progesterone receptors, and they do not make any or much of the HER2 protein. The cells test negative on all three of these tests, giving TNBC its name.

TNBC is an aggressive type of breast cancer that is more likely than other types to be at a later stage at the point of diagnosis. It is also more likely to recur.

Keep reading to learn more about TNBC, including who it affects and the outcome for people with this condition.

Overall, breast cancer is reasonably common. Research suggests that there are more than 280,000 new cases each year in the United States.

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Infographic by Diego Sabogal

TNBC accounts for about 10–20% of all breast cancers.

The National Cancer Institute’s (NCI’s) Surveillance, Epidemiology, and End Results (SEER) Program shows that TNBC affects 13 in every 100,000 females in the U.S.

Various risk factors raise the likelihood of developing TNBC.

These include:

  • Race: Black and Latinx people are more likely to receive a TNBC diagnosis than white people.
  • Age: TNBC is more likely to present in people below the age of 50 years.
  • Weight: Obesity increases the risk of receiving a diagnosis of TNBC.
  • Genetic mutations: The BRCA1 gene mutation puts someone at higher risk of TNBC.

Research shows that Black women’s risk of TNBC is 2.7 times as high as that of white women. This might be due, at least in part, to social factors.

Another factor is that in the U.S., obesity disproportionately affects Black people. Recent research suggests that 57.2% of African American women in the U.S. have obesity compared with 38.2% of non-Hispanic white women.

The researchers believe that obesity among Black women could be a contributing factor to the higher rates of TNBC among this group. They note that about 16.8% of African American women have a body mass index (BMI) greater than 40 compared with 9.7% of non-Hispanic white women.

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Infographic by Diego Sabogal

Obesity increases the risk of developing TNBC. A 2016 study found that premenopausal women with a BMI of 30 or above had an 82% higher risk of developing TNBC compared with women with a BMI below 25. The participants in the highest weight quartile had a 79% increased risk of TNBC compared with those in the lowest quartile.

Additionally, the BRCA1 gene helps suppress the growth of tumors. In women with a mutation in the BRAC1 gene, breast cancer is more common, as is TNBC specifically.

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Infographic by Diego Sabogal

According to the NCI, in the general population, about 13% of females will receive a diagnosis of breast cancer in their lifetime. Among those with the BRCA1 mutation, 55–72% will have breast cancer by the age of 70–80 years.

Chemotherapy is typically the first-line treatment for TNBC. Other treatment options include surgery, radiation therapy, and targeted drugs.

TNBC often responds well to chemotherapy in the beginning, but even with treatment, it can still return. TNBC is more likely to recur than other forms of breast cancer.

A 2019 study found that 40% of people with stage 1 to stage 3 TNBC will experience a recurrence of their cancer even after standard treatments.

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The outlook for people with TNBC is better for white people than Black people. African American women are 28% more likely to die from TNBC than white women.

Research also suggests that people of different races with TNBC receive different standards of care and treatment.

A 2021 study found that African American women were 31% less likely to receive surgery for their TNBC than white women with the same diagnosis. They were also 11% less likely to receive chemotherapy.

The SEER database provides data on the survival of people who received a TNBC diagnosis between 2011 and 2017.

The overall 5-year relative survival rate for TNBC, combining all stages of the disease, is 77%. This statistic shows the likelihood of a person with TNBC living for 5 years after their diagnosis compared with people without the disease.

The SEER statistics also show the following 5-year relative survival rates:

  • 91% for people with localized TNBC that has not spread beyond the breast.
  • 65% for people with regional TNBC that has spread to nearby lymph nodes and other structures.
  • 12% for those with distance TNBC that has spread to distant organs in the body.

These are the most recent data available, but it is important to note that people who receive a diagnosis now may have a better outlook due to advances in knowledge and treatment.