Trends in Pathologic Complete Response After Treatment with Neoadjuvant Chemotherapy for Breast Cancer Among Racial Minority Groups

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Based on systemic therapy improvements, in recent clinical trials following neoadjuvant chemotherapy, pathologic complete response (pCR) rates were more than 60% in patients with breast cancer, especially in patients with human epidermal growth factor receptor 2 (HER2)-positive and triple-negative breast cancer.

Although being treated with standard of care in prospective studies, racial minority groups experienced worse survival outcomes, and in clinical trials they were underrepresented. Ma and colleagues conducted an observational cohort study to address gaps in understanding to assess pCR and survival outcomes stratified by racial and ethnic groups.

Data were extracted from the National Cancer Database for female patients with stage I-III breast cancer who were diagnosed between 2010 and 2017 and treated with neoadjuvant chemotherapy followed by surgery. The longitudinal trend of pCR over time was evaluated.

This was a large study that included a total of 105,804 patients (n = 72,631 for non-Hispanic white [NHW], n = 7632 for Hispanic white [HW], n = 19,505 for black, n = 4393 for Asian or Pacific Islander [API], n = 1643 for other race). The median follow-up was approximately 49.2 months. The overall pCR rate rose from 15.1% in 2010 to 27.2% in 2017, mainly driven by hormone receptor (HR)-negative, HER2-positive tumors (28.6%-53.1%; all trend P <.001) and API women (15.7%-31.6%). When compared with NHW women, HW women were more likely to have pCR for HR-negative, HER2-positive (P = .02) and HR-positive, HER2-positive tumors (P = .005). Black women were more likely to have pCR for HR-positive, HER2-negative tumors (P = .01) and less likely for HR-negative, HER2-positive (P <.001) and triple-negative tumors (P <.001).

For HR-negative, HER2-positive tumors, API women were more likely to have pCR compared with NHW women (P = .04). When compared with NHW women, HW women and API women experienced improved overall survival and black women were associated with worse overall survival.

This is the largest study using a nationwide oncology database that suggests that over time for all racial cohorts there is an improving trend of pCR rate. HW and API women were more likely to have pCR for select HER2-positive tumors when compared with NHW women; black women were less likely to have pCR for HR-negative, HER2-positive and triple-negative tumors but not for HR-positive, HER2-negative tumors. While black women experienced worse survival only for residual nodal disease, improved survival in the setting of any residual disease was associated with HW and API women when compared with NHW women.

Source:

Ma SJ, Yu B, Serra LM, et al. Racial differences, and trends in pathologic complete response following neoadjuvant chemotherapy for breast cancer. Presented at: American Society of Clinical Oncology 2021 Annual Meeting, June 4-8. Abstract 575.

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