In Triple-Negative Breast Cancer, Response to Chemotherapy Before Surgery Varies by Race and Ethnicity
Among women diagnosed with triple-negative breast cancer, the chances of having what’s called a pathologic complete response (pCR) after chemotherapy before surgery — called neoadjuvant chemotherapy — seems to be linked to race and ethnicity. Compared to white women, Black women are less likely to have a pCR and Hispanic women are more likely.
The research was published online on Feb. 23, 2024, by the Journal of Clinical Oncology. Read the abstract of “Racial/Ethnic Disparities in Pathologic Complete Response and Overall Survival in Patients With Triple-Negative Breast Cancer Treated With Neoadjuvant Chemotherapy.”
What is pCR?
One way doctors judge the effectiveness of treatments before surgery is to look at the tissue removed during surgery to see if it contains any actively growing cancer cells. If there are none, it’s called a “pathologic complete response,” or pCR.
A number of studies have shown a link between pCR after neoadjuvant chemotherapy for breast cancer and better disease-free survival, as well as better overall survival.
Disease-free survival is how long a person lives without the breast cancer coming back. Overall survival is how long a person lives, whether or not the breast cancer comes back.
Why do the study?
Although overall breast cancer survival has improved during the past 20 years, there are still racial and ethnic disparities in outcomes. From 2015 to 2019, breast cancer death rates among Black women were 41% higher than they were among white women. While these differences seem to be caused by a number of factors, including access to treatment and socioeconomic issues, there is also evidence that differences in the biology of the breast cancers contribute to the difference in outcomes. Black women are twice as likely to develop triple-negative breast cancer, the most aggressive type, than white women and are more likely to die from the disease.
Because triple-negative breast cancer has no hormone receptors or HER2 receptors, chemotherapy and immunotherapy are the two primary treatments for it. Still, the researchers who did this study noted that minority women were dramatically under-represented in the clinical trials that studied chemotherapy for triple-negative breast cancer. So any differences in how minority women responded to chemotherapy weren’t noticed because the trial participants weren’t diverse.
Some small studies have suggested that the response to neoadjuvant chemotherapy for triple-negative breast cancer varies by race and ethnicity. The researchers did this larger study to get more information about that.
About the study
Researchers from the Duke University School of Medicine searched the National Cancer Database for women who were diagnosed with triple-negative breast cancer and received neoadjuvant chemotherapy and then had surgery between 2010 and 2019.
The National Cancer Database contains information on cancer diagnoses, treatments, and outcomes collected in more than 1,500 U.S. facilities accredited by the Commission on Cancer. The database is a joint program of the American College of Surgeons and the American Cancer Society.
Overall, the researchers analyzed information from 40,890 women:
26,150 were white
9,672 were Black
3,267 were Hispanic
1,368 were Asian
433 were of another race or ethnicity
The women ranged in age from 44 to 61; about 60% were age 50 or older. Follow-up time was about 55 months.
Compared to tumors in white women, breast cancer tumors in Black women and Hispanic women at diagnosis were:
larger
higher grade
more likely to have spread to the lymph nodes
Overall, 29.8% of the women had a pCR after neoadjuvant chemotherapy. pCR rates by race or ethnicity were:
32.57% for Hispanic women
30.51% for white women
29.79% for women of another race or ethnicity
28.8% for Asian women
26.96% for Black women
Other factors that affected pCR rates were:
a longer time between diagnosis and starting neoadjuvant chemotherapy made pCR less likely
being younger than 50 made pCR more likely
having other health conditions made pCR less likely
receiving treatment at a community facility made pCR less likely
having a larger tumor and positive lymph nodes made pCR less likely
Among the women who had a pCR, the five-year overall survival rate was 91.7%, compared to 66.7% for women who didn’t have a pCR.
There was almost no difference in overall survival rates between Black women and white women who had a pCR — both were about 91% — but overall survival rates were slightly higher for Hispanic women (93.7%) and Asian women (94%) who had a pCR.
“Understanding the influences, including biologic factors that may contribute to these observed differences in outcomes, is paramount to improving treatment strategies and survival for patients with this otherwise aggressive breast cancer subtype,” the researchers wrote.
What this means for you
This large study shows that pCR rates vary by race and ethnicity. It also shows that the link between pCR and overall survival does not vary by race and ethnicity. The results strongly suggest that the disparities in overall survival for Black women with breast cancer are probably partly related to lower pCR rates after neoadjuvant chemotherapy.
More research is needed to understand why Black women are less likely to have a pCR after neoadjuvant chemotherapy for triple-negative breast cancer. We also need more research to find more effective treatments for triple-negative breast cancer, especially in Black women.
If you’re a Black woman who’s been diagnosed with breast cancer, you may want to consider enrolling in a clinical trial. According to 2020 numbers from the American Cancer Society and Centers for Disease Control, 12% of new cancer cases in the United States were diagnosed in Black people, but Black patients made up only 3% of the participants in breast cancer clinical trials that led to new drug approvals.
If the population of people in clinical trials doesn’t reflect the diversity of our society, then we can’t ensure that the results apply to everyone.
Listen to the episode of The Breastcancer.org Podcast featuring Dr. Nadine Barrett explaining why diversity in clinical trials is so important.
The Importance of Diversity in Breast Cancer Clinical Trials
Sep 15, 2021Updated on July 18, 2024