Triple-negative breast cancer accounts for around 10–20% of all breast cancer cases. New treatments may improve the chance of curing the cancer or improving a person’s outlook.

Breast cancer takes different forms. It can be hormone receptor-positive or hormone receptor-negative, depending on whether or not the cancer cells have estrogen or progesterone receptors.

Breast cancer cells can also be positive or negative for the human epidermal growth factor (HER2) protein.

Triple-negative breast cancer, which occurs in 10–20% of breast cancers, refers to when the cancer cells are negative for hormones and the HER2 protein. In other words, the cancer cells do not have receptors for:

  • estrogen
  • progesterone
  • the HER2 protein

The lack of receptors on the cancer can make it more difficult to treat, as therapies that target the receptors are not effective.

According to the American Cancer Society, high risk groups include women who:

  • are under the age of 40 years
  • are of African American descent
  • have a BRCA1 mutation

Triple-negative breast cancer can grow faster than other cancers, and it has a higher rate of relapse.

“There are a lack of targets and some drug resistance,” Dr. Jack Jacoub, the medical director of the Memorial Care Cancer Institute at Orange Coast Medical Center in Fountain Valley, CA, told Medical News Today.

“There are so many pathways going on in the cancer cell,” he added, “and we can’t manipulate it the way we can with HER2 and other types of breast cancer.”

Researchers are developing new treatments that work for triple-negative breast cancer.

The Centers for Disease Control and Prevention (CDC) identify a few treatment options for triple-negative breast cancer. These include:

  • lumpectomy, or the removal of the tumor while leaving most of the breast intact
  • mastectomy, or the removal of the breast and some surrounding tissue
  • chemotherapy
  • radiation therapy

Triple-negative breast cancer is more responsive to immunotherapy than other forms of breast cancer. Immunotherapy helps the immune system find and attack the cancer cells.

People commonly use atezolizumab, a monoclonal antibody medication, to treat triple-negative breast cancer. Pembrolizumab, another monoclonal antibody, has also shown promise in trials for early stage triple-negative breast cancer.

Dr. Xinyu Nan, a medical oncologist with the Center for Cancer Prevention and Treatment at the Providence St. Joseph Hospital in Orange County, CA, told MNT that antibody drug conjugates are effective at targeting the cancer.

Antibody drug conjugates contain an antibody linked to a small molecule drug that is toxic to the tumor cell.

The antibody drug conjugate delivers a molecule through an intravenous line that attaches to the cancer cells. These molecules help the chemotherapy better target the cancer cells.

According to Dr. Crystal Fancher, the lack of receptors to target mean that some treatments for other forms of breast cancer are not effective for triple-negative breast cancer.

Dr. Fancher is a surgical breast oncologist at the Margie Petersen Breast Center at Providence Saint John’s Health Center and an assistant professor of surgery at Saint John’s Cancer Institute, both in Santa Monica, CA.

“Unlike other breast cancers that have hormone receptors, like HER2, triple-negative is harder to treat,” she told MNT.

Dr. Jacoub explained that people’s outcomes tend to improve when they use chemotherapy in combination with other treatments. A course of treatment now typically includes “immunotherapeutics, which we use before and after surgery as well as during a recurrence,” he added.

Platinum chemotherapy, or chemotherapy using platinum-based drugs, is common in the treatment of triple-negative breast cancer due to its effectiveness. However, research has shown that severe side effects can limit its use.

One 2018 study found around 40 specific side effects, including a decrease in bone marrow production, problems with kidney function, headaches, and other negative effects on the nervous system. There are some treatments available to address these side effects.

Dr. Nan estimated that about 40% of people can use a combination of immunotherapy and chemotherapy.

There are several new and ongoing studies looking at treatments for triple-negative breast cancer.

Dr. Fancher encouraged people with triple-negative breast cancer to look into trials. “Research on clinical trials is really important,” she told MNT.

“If you [have] triple-negative breast cancer, consider a clinical trial. It helps move the research forward. There are lots of trials out there, and many are having good results.”

Dr. Nan spoke about the Keynote 522 clinical trial. This trial is looking at the use of pembrolizumab, a type of immunotherapy, in combination with chemotherapy before and after surgery.

The trial focuses on people with stage 2 or 3 breast cancer who are at high risk, and pembrolizumab has shown some promise. In fact, the trial has shown a 65% effectiveness rate, indicating no residual signs of cancer in the tissue. This is up from 51% previously.

The phase 3 ASCENT clinical trial is looking at the use of sacituzumab govitecan, an antibody drug conjugate. In a phase 2 trial, it had shown promise in people who had previously received treatment for metastatic triple-negative breast cancer. The Food and Drug Administration (FDA) gave the drug accelerated approval in 2020.

People who are interested in learning more or potentially joining a clinical trial can look at At any time, there are likely several ongoing or recruiting studies across the country. Details about signing up or getting more information on triple-negative breast cancer clinical trials are available here.

A person should talk with a doctor before joining a clinical trial. They may be able to help the person find a relevant study or recommend ones that will work best for them.

Triple-negative breast cancer is curable when a doctor diagnoses it during the first three stages (1–3), said Dr. Jacoub. He treats stages 1–3 with everything he can in order to remove and destroy the cancer.

However, the ability to cure triple-negative breast cancer is hindered by recurrence or metastasis past the lymph nodes. Triple-negative breast cancer is the most likely form of breast cancer to return.

The outlook for people with localized triple-negative breast cancer over a 5-year period is good. Around 91% of people will survive to the 5-year mark.

If the cancer spreads to local tissue or lymph nodes, however, the 5-year survival rate drops to 65%. If it spreads to other organs or tissue, the rate falls to 12%.

These figures are based on data for people who received treatment in the past. Newer methods have changed the outlook, which will continue to shift as different treatments become available.

Anecdotally, Dr. Nan has a segment of patients who have responded to immunotherapy treatment for longer than 5 years.

“Maybe if [his practice] follows these [people] long enough, some may still be alive after more than 10 or 15 years, then we can say [their cancer is] cured,” he said. “With developed or newer types of immunotherapy, [we] may be able to cure stage 4 cancer in the future.”

Dr. Jacoub agreed that the outlook is changing with newer treatments. He also noted that although some people have a reduced quality of life while undergoing treatment, others can maintain a good quality of life.

Triple-negative breast cancer is an aggressive form of breast cancer that may not respond to treatments that are effective against other forms of breast cancer.

With early detection, a doctor may be able to cure it with aggressive treatment. When a doctor diagnoses it after it has already spread, there is no current cure, but some treatments can help a person live longer with a better quality of life.

People with triple-negative breast cancer should try to find a doctor who is up to date on the latest treatments or who can help identify new clinical trials that may help.