Correlation of Histopathological and Radiological Response Patterns and Their Prognostic Implications in Breast Cancer After Neoadjuvant Chemotherapy.

Purpose: In breast cancer (BC), neoadjuvant chemotherapy (NAC) responses can be categorized as concentric shrinkage (CS), non-concentric shrinkage (non-CS), and complete response, influencing surgical planning and survival. This study evaluates the correlation between histopathological and radiological response patterns in BC patients after NAC and their impact on overall survival (OS) and disease-free survival (DFS).

Patients and methods: This retrospective study analyzed 168 BC patients who received NAC between 2018 and 2022. Tumor response was evaluated radiologically using MRI and histopathologically after surgery. Radiological response patterns were categorized into CS, non-CS, and radiological complete response (rCR). Histopathologically, patients were classified into CS, non-CS, and pathological complete response (pCR). Concordance between radiological and histopathological classifications was assessed using the kappa statistic. Survival outcomes, including OS and DFS, were analyzed using Kaplan-Meier methods.

Results: Histopathological response patterns were distributed as CS (31.5%), non-CS (34.5%), and pCR (34%). Moderate agreement was observed between radiological and histopathological assessments (κ: 0.439, p < 0.001). Radiological evaluation identified 64% of CS, 50% of non-CS, and 74% of pCR cases accurately. Tumor molecular subtypes significantly correlated with both radiologic and histopathologic response patterns (p < 0.001). Subtype analysis revealed higher pCR rates in TN, HER2-enriched, and Luminal B-HER2(+) tumors, while non-CS was predominant in Luminal A tumors. No significant correlation was observed between histopathological or radiological patterns and OS (p: 0.291, p: 0.515) or DFS (p: 0.599, p: 0.899). However, patients achieving pCR tended to have better survival outcomes.

Conclusion: We observed moderate concordance between histopathological and radiological response patterns in BC patients after NAC, but discrepancies highlight the limitations of radiological evaluation alone. These patterns did not significantly correlate with prognosis. Higher pCR rates were associated with better outcomes, but response patterns alone may not predict survival, warranting further research in larger cohorts.