3 Important Things to Know About Triple-Negative Breast Cancer

This Triple-Negative Breast Cancer Day, learn more about this aggressive form of breast cancer that’s a major priority for BCRF

Triple-negative breast cancer (TNBC) is a major focus of BCRF’s annual investment in research. But what is it?

About 10 to 15 percent of breast cancer diagnoses are classified as triple-negative, meaning that they lack the three common growth drivers: estrogen and progesterone receptors and the HER2 protein. For patients whose breast cancers express all or some of these markers, there are targeted therapies that halt their cancers’ growth.

Since TNBC isn’t fueled by these markers, lifesaving targeted treatments like Herceptin and hormonal therapy aren’t effective. What’s more: TNBC is more common in groups like younger women and Black women, who already tend to experience worse outcomes after a diagnosis.

This is why BCRF makes TNBC a priority. To improve outcomes for patients diagnosed with TNBC, we need more treatments and to understand why the disease strikes younger women and Black women especially. But the good news is that, thanks to research, TNBC has more treatments than ever and our understanding of this form has grown by leaps and bounds in just a few short years.

As we mark TNBC Day on March 3, here are three things to know about this form right now.

1. TNBC is an urgent women’s health issue.

TNBC tends to be more aggressive and fast-growing. It’s more likely to be diagnosed at a later stage and to recur (come back after initial treatment). It’s also more likely to be diagnosed in women with BRCA1/2 gene mutations.

This form is also more commonly diagnosed in women under 40—a group that isn’t commonly screened. While rare, when women under 40 are diagnosed with breast cancer, they’re nearly 40 percent more likely to die from the disease than women over 40. And to the alarm of experts, breast cancer incidence rates have been rising faster in younger women (under 50) than in older women.

Black women are 38 percent more likely to die from breast cancer compared to white women. One of the reasons for this devastating disparity is the fact that they’re far more likely to be diagnosed with triple-negative breast cancer. About one in five breast cancer diagnoses in Black women is triple-negative, compared to one in 10 in all other women, according to data from the American Cancer Society.

2. Once lacking targeted therapies, TNBC now has a growing number of options.

Without highly effective targeted therapies like those that treat hormone- and HER2-positive breast cancers, TNBC patients were limited to just surgery, chemotherapy, and radiation for a long time. Where doctors once said that TNBC lacked any targeted therapies, now they can say that TNBC has a small but growing number now.

Since just 2018, TNBC patients who have inherited BRCA1/2 mutations (about 15 percent of patients) have benefitted from PARP inhibitors. The groundbreaking immunotherapy drug pembrolizumab (Keytruda^®), a checkpoint inhibitor that’s combined with chemotherapy, was approved for metastatic TNBC in 2020 and high-risk, early-stage TNBC in 2021—a significant advancement for patients.

One of the most exciting new developments in breast cancer treatment—antibody-drug conjugates (ADC)—are proving to be effective for metastatic TNBC. In 2020, the ADC sacituzumab govitecan (Trodelvy^®) was approved for metastatic TNBC. In 2022, a breakthrough ADC called trastuzumab durextecan (Enhertu®) made headlines for targeting low levels of HER2. Until then, patients who had low levels of HER2 were classified as HER2-negative because no prior HER2-targeted therapy was effective. Just weeks ago, the FDA approved trastuzumab durextecan for not only metastatic HER2-low breast cancer but now HER2-ultralow. TNBC patients and others whose tumors actually have low and ultralow levels of HER2 will now benefit.

While there’s been tremendous progress for both early-stage and metastatic TNBC, not all of these treatments benefit all TNBC patients. They urgently need more options.

3. TNBC research is rapidly accelerating.

Research is the reason that the FDA has approved these five new therapies for TNBC in just the seven years. It’s the reason that patients with metastatic TNBC are learning that their tumors are not, in fact, HER2-negative at all, but that there’s a treatment that can target the low and ultralow levels of HER2 in their tumors—a development that once didn’t seem possible. We’re learning more about this form all the time—knowledge that will lead to new treatments and improvements in care.

BCRF is at the forefront of this research—supporting the field’s foremost TNBC researchers, clinical trials, and studies that will improve outcomes and save lives.