1054 – Predictors of axillary response after neoadjuvant chemotherapy in breast cancer: a clinicopathological analysis

Abstract

Introduction: Neoadjuvant chemotherapy in patients with breast cancer and clinically positive axillary lymph nodes
(cN+) aims to achieve conversion to a pathologically negative status (ypN0), which is associated with better prognosis
and possible surgical de-escalation.
Objective: This study aimed to evaluate clinicopathological predictors of axillary response after neoadjuvant chemotherapy to allow for individualized therapy.
Methods: This retrospective analytical study was conducted at a tertiary public breast cancer center. Initially, 587 patients
were evaluated, with 129 patients included after applying the selection criteria (invasive ductal carcinoma, non-metastatic
disease, cN+ axilla, and treatment with a doxorubicin plus cyclophosphamide followed by a taxane [AC-T] regimen). The
following variables were analyzed: age, histological grade, tumor subtype (luminal, triple-negative, HER2), Ki67 (<20%
vs. ≥20%), and pre-treatment clinical axillary status (cN). The outcome was pathologic complete response (pCR). The chisquare test, Cramer’s V, and standardized residuals were used for analysis (p<0.05).
Results: The mean age was 50.3 years. The pCR rate was 54.3% (70/129). There was a significant association between tumor
subtype and pCR (χ²=12.54; p=0.002; V=0.31), with a higher response in triple-negative tumors and a lower response in
luminal tumors. Initial axillary status was also associated with pCR (χ²=11.32; p=0.003; V=0.30), with a higher response
in cN1 and a lower in cN2. There was no significant association with age (p=0.68), Ki67 (p=0.21), or histological grade
(p=0.40), although there was a trend toward a higher response in high-grade tumors.
Conclusion: Tumor subtype and initial clinical axillary status were significant predictors of response to neoadjuvant
chemotherapy, with a higher probability of response in triple-negative tumors and among cN1 patients, potentially allowing for less aggressive surgical strategies.
Ethics: Research Ethics Committee Approval (CAAE 52999321.4.0000.5149).