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Racial Disparities in Triple-Negative Breast Cancer Outcomes

Racial Disparities in Triple-Negative Breast Cancer Outcomes
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Published on June 11, 2021

Researchers Seek to Understand Racial Disparities in TNBC

There are notable differences in how women of different racial and ethnic backgrounds are treated for triple-negative breast cancer (TNBC), as well as the disease outcomes they experience. But the reasons for these variations are unclear.

TNBC is an aggressive subtype of breast cancer that, unlike other breast cancer subtypes, does not have estrogen receptor (ER), progesterone receptor (PR), or an amplification of ERBB2 (more commonly known as HER2). The TNBC subtype accounts for 10 to 15 percent of all breast cancer diagnoses.

Chemotherapy, surgery, and radiation are the go-to treatment options since hormone-targeted therapies do not work for this patient population. TNBC has a worse prognosis than hormone-receptor-positive breast cancer, with higher risks of recurrence, distant metastasis, and mortality, particularly within the first 5 years after diagnosis.

Examining the Disparities

A recent study, published in the journal JAMA Oncology, examined the differences in clinical treatment and outcomes between African American and non-Hispanic white women with TNBC to see if sociodemographic, clinical, and location-based factors in rural and urban areas in the United States contribute to outcome disparities.

The study included 23,123 women diagnosed with nonmetastatic TNBC between Jan. 1, 2010, and Dec. 31, 2015, and followed up through Dec. 31, 2016. The women were identified from the Surveillance, Epidemiology, and End Results (SEER) data set, a program run by the National Cancer Institute, to provide information on cancer statistics.

Of the participants, 5,881 (25.3%) were African American women and 17,332 (74.7%) were white women. Compared with white patients, African American patients had lower odds of receiving surgery and chemotherapy after adjustment for sociodemographic, clinicopathologic (signs and symptoms observed by a doctor), and county-level factors.

African American women were younger than white women at diagnosis (56.3 years vs 59.7 years), more likely to be insured through Medicaid (20.6% vs 8.8%), and more likely to live in low-income counties (14.7% vs 7.1%) and urban counties (92.1% vs 86.2%).

“Chemotherapy delay and incompletion of chemotherapy may occur more frequently in African American patients, compared with white patients,” Ying Liu, MD, PhD, an assistant professor at the Washington University School of Medicine, told Patient Power. She cited several reasons that contribute to this.

“Comorbid health conditions, such as obesity, type 2 diabetes, and lifestyle factors, including alcohol consumption, physical inactivity, may also contribute to the observed disparities in TNBC survival,” Dr. Liu said.

However, researchers are still unable to completely explain the excess mortality risk in African American women with TNBC due to a lack of data on these contributing factors, according to Dr. Liu.

Chemotherapy Resistance May Play a Role

Dr. Lui and her team found that there was a higher risk of breast cancer mortality in the African American patient cohort than in the white cohort. Genetics may play a role in how chemotherapy works in different ethnic backgrounds, she explained.

Another study, published in the Journal of Clinical Oncology, reported that African American patients with TNBC had a lower likelihood of a pathological complete response to neoadjuvant (given before surgery) chemotherapy, compared to white patients. This suggests that African American women may be more resistant to chemotherapy than white women.

Dr. Liu sees an opportunity to analyze this issue further.

“I’m working with tumor biologists to examine the possible biological differences between triple-negative breast tumors of African American women and triple-negative breast tumors of white women. I hope this study will refine our understanding of racial disparities in this aggressive subtype of breast cancer,” she said.

Understanding TNBC at the tumor level may lead to improved outcomes.

“Future studies should examine the molecular characteristics of triple-negative breast tumors that regulate the response to chemotherapy and their role in explaining racial disparities in triple-negative breast cancer outcomes observed in this study,” Dr. Liu said.

Is Racism a Contributing Factor?

Dr. Liu’s study did not specifically study systemic racism as a contributing factor, although it is well known that marginalized groups tend to have fewer positive experiences in the healthcare setting. Anti-racism programs are being developed and implemented across treatment centers, according to a recent article in the International Journal of Environmental Research and Public Health, which offers recommendations for improving these conditions.

“Anti-racism interventions will need to be tailored to the communities being served by healthcare settings, and this cannot be done without centering the voices and experiences of [BIPOC] staff, patients and communities,” researchers wrote in the article.

Whether these disparities are due to racial bias, socioeconomic factors, the tumor microenvironment, or some combination, supporting African American women in seeking screening and finding effective treatment plans is crucial in reducing TNBC disparities.

~Lauren Evoy Davis

See Our Sources:

Original Investigation of Outcomes in Breast Cancer “Evaluation of Racial/Ethnic Differences in Treatment and Mortality Among Women With Triple-Negative Breast Cancer.” JAMA Oncology. (2021).

Breast Cancer Outcomes. “Differences in the Use and Outcome of Neoadjuvant Chemotherapy for Breast Cancer: Results From the National Cancer Data Base.” Journal of Clinical Oncology. (2015).

Racism in Health Care. Implementing Anti-Racism Interventions in Healthcare Settings: A Scoping Review. International Journal of Environmental Research and Public Health. (2019).

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