If you’re living with stage 4 triple-negative breast cancer (TNBC) — also called metastatic triple-negative breast cancer — you may feel uncertain about the future. (Cancer stages are sometimes noted with Roman numerals — in this case, stage IV.) Maybe you have questions around what to expect or how much time you have to spend with your loved ones. Stage 4 is the most advanced stage of breast cancer. It’s important to understand the factors that impact survival rates in stage 4 TNBC.

TNBC is a type of breast cancer that’s challenging to treat. This is partly because the cancer cells don’t have the following proteins:

• Estrogen receptor (ER)
• Progesterone receptor (PR)
• Human epidermal growth factor receptor 2 (HER2)

These receptors, which are types of proteins, can be used as targets for treatment. Since TNBC breast cancer cells don’t have HER2 or hormone receptors to target, TNBC has fewer treatment options. Compared to other subtypes of breast cancer, TNBC often grows and spreads more quickly and has a poor prognosis (outlook).

This article will cover survival rates in TNBC and different factors that can affect your prognosis. Talk with your doctor about any questions or concerns you may have — they can help you better understand your individual situation.

Measuring TNBC Survival Rates

To better understand cancer prognosis, researchers often look at survival rates in large groups of people. Depending on the questions they’re asking, different types of survival rates may be used.

Five-Year Relative Survival

Many times, researchers want to compare the survival of people with a specific type of cancer to people in the general population. To do this, they might look at the five-year relative survival rate. This is a calculation that compares how likely people with the particular type of cancer are to be alive after five years relative to people in the general population.

The Surveillance, Epidemiology, and End Results Program (SEER) database provides the National Cancer Institute with data to keep track of cancer survival rates. According to the American Cancer Society, the five-year relative survival rate for metastatic TNBC is 12 percent. This means that people with stage 4 disease are about 12 percent as likely as the general population to still be alive in five years.

Overall Survival

Another way to look at TNBC prognosis is overall survival. This measures the percentage of people with a certain cancer who are still alive after a period of time — usually five years. It’s important to note that overall survival simply looks at whether people with cancer are alive or have died rather than the specific cause of death.

Overall survival rates may be different across different study populations. In studies done in Western populations, the five-year overall survival rate for stage 4 TNBC has ranged from 4 percent to 20 percent. This means that up to 20 percent of people with stage 4 TNBC are expected to still be alive five years after diagnosis.

Progression-Free Survival

In clinical trials that are testing possible new treatments for cancer, progression-free survival may be used to figure out how well the treatment is working. Progression-free survival refers to how long people can live without the cancer getting worse. This measurement can help you to know whether a cancer treatment might help you live longer without your cancer progressing.

Risk Factors That Affect TNBC Survival Rates

While being diagnosed at a young age doesn’t necessarily mean a worse outcome, other risk factors — as well as a person’s medical history — can affect one’s TNBC prognosis.

Race and Ethnicity

Compared to non-Hispanic white women in the United States, African American women have a higher risk of being diagnosed with TNBC, according to research from Frontiers in Public Health. African American women are also more likely to be diagnosed with stage 4 TNBC and die from the disease compared to non-Hispanic white women, according to the research. Hispanic women may also be more likely than non-Hispanic white women to be diagnosed with advanced disease, according to research in the Journal of Women’s Health.

Researchers don’t fully understand why TNBC leads to lower survival among members of certain racial and ethnic groups. Research has shown that being low-income and having reduced access to health care might lead to worse outcomes in people with TNBC. Lifestyle and genetics may also play a role. While research is helping to address these issues, there’s still a long way to go. More work is needed to achieve equitable access to treatment and improve survival across all populations.

Response to Prior Treatment

In many cases, TNBC comes back — or relapses — after treatment. It may also be refractory to treatment, meaning it doesn’t respond well to therapy. Relapsed or refractory metastatic TNBC has a poor prognosis — about half the people with the disease will die within nine to 17 months, according to research published in the Annals of Translational Medicine.

Where in the Body Cancer Has Spread

In stage 4 TNBC, breast cancer cells spread and form tumors in other parts of the body. Where these distant tumors end up can impact your prognosis.

One study in Neoplasma compared overall survival rates across different sites (locations) of metastasis. Researchers found that when the cancer first spread to the brain, it led to the shortest survival time. On the other hand, when the cancer spread first to the lung or the bone, people had the longest survival rates. These results show that your prognosis can depend a lot on where metastasis first occurs.

Read more about how sites of metastasis affect prognosis.

Other Health Problems

Underlying health issues and lifestyle factors may also affect your chance of survival. A study — published in the Journal of Korean Medical Science — found that people with TNBC who had higher body mass index (BMI) scores had a worse prognosis than those with lower BMI scores. This may be partly due to the fact that fat cells can cause inflammation, which can promote the growth of cancer cells.

Know Your Options

Though the outlook for stage 4 TNBC may not look very positive, you shouldn’t lose hope. Reach out to your oncology care team to learn how you can improve your chance at a longer life.

Treatment Options

Chemotherapy is usually the first-line treatment for metastatic TNBC — either on its own or in combination with other cancer treatments. If your cancer doesn’t respond well or relapses after treatment, or if you’ve already had chemotherapy, your oncologist (cancer specialist) may recommend a different type of breast cancer treatment.

Although hormone therapies and drugs like trastuzumab (Herceptin) aren’t useful for treating TNBC, other types of targeted therapies can help. A targeted therapy is a drug that affects only one protein or group of proteins.

Your doctor may recommend immunotherapy drugs that can specifically target certain proteins in cancer cells. Sacituzumab govitecan-hziy (Trodelvy) contains a monoclonal antibody that targets and binds to a protein called trophoblast cell-surface antigen 2 (TROP2) on cancer cells. It then delivers a drug into the cell that causes its death. The drug is indicated to treat advanced or metastatic TNBC if surgery isn’t an option and after at least two other therapies have been tried.

If you have a mutation in the BRCA1 or BRCA2 gene, your doctor may prescribe a drug like olaparib (Lynparza) or talazoparib (Talzenna). These are PARP inhibitors, a type of targeted drug that can be effective in people with BRCA mutations.

Lifestyle Changes

Making some lifestyle changes may improve your prognosis. There’s some evidence that exercise and certain diet changes can improve survival in people with TNBC. Your cancer care team can work with you to come up with a treatment plan that can help you live a longer, healthier life.

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 discussed your risk factors with your doctor? Do you have more questions about survival rates in triple-negative breast cancer? Share your experiences in the comments below, or start a conversation by posting on your Activities page.