Determinants of pathologic complete response in early-stage triple-negative breast cancer at a single institution.

Abstract

e12664 Background: Triple-negative breast cancer (TNBC) has been widely reported as having worse outcomes among Black women. However, Black women remain markedly underrepresented in clinical trials, limiting the generalizability of these conclusions and raising concern that observed disparities may reflect inequities in access to high-quality care rather than tumor biology alone. Pathologic complete response (pCR) following neoadjuvant therapy is a validated surrogate for long-term outcomes. Using real-world data from a racially and socioeconomically diverse population, we evaluated whether race and care-related factors were associated with achieving pCR in stage II–III TNBC. Methods: We conducted a single-institution retrospective cohort study using real-world data to evaluate factors associated with pCR following neoadjuvant therapy in stage II–III TNBC. Analyses followed a prespecified, internally reviewed plan developed prior to data extraction and statistical evaluation. Data was extracted from electronic health records in the REDCap electronic database. Eligible patients received neoadjuvant systemic therapy with curative intent and had evaluable surgical pathology. The primary endpoint was pCR. Multivariable logistic regression was used to evaluate associations between pCR and race, zipcode income, clinical stage, treatment regimen, and time-to-care metrics. Results: Among 72 patients with stage II–III TNBC (75% Black), the overall pCR rate was 44%. Race was not associated with pCR on unadjusted analysis (Fisher's exact p = 1.00) and remained non-significant after adjustment. Neoadjuvant chemoimmunotherapy (CIO) was associated with higher pCR compared with chemotherapy alone in the overall cohort (58.3% vs 35.4%; Fisher's exact one-sided p = 0.055). Among Black patients (n = 55), pCR rates were similarly higher with CIO compared to chemotherapy (62.5% vs 33.3%; one-sided p = 0.046). Beyond pCR, residual cancer burden analysis showed 44% achieved RCB-0, 44% RCB-1, and 13% RCB-2/3. Conclusions: In this predominantly Black, socioeconomically diverse TNBC cohort, race was not independently associated with pCR when contemporary neoadjuvant therapy was delivered. CIO was associated with a large, clinically meaningful absolute increase in pCR rates across both the overall cohort and Black patients, with consistent effect sizes despite borderline statistical significance, likely reflecting limited sample size. These findings support the hypothesis that treatment regimen and access to high-quality care, rather than race, drive early response outcomes in TNBC. The high proportion of patients achieving minimal residual disease further highlights favorable outcomes in this diverse urban population and underscores the need for larger studies to better define the impact of healthcare delivery on disparities in TNBC outcomes.