Combined Pathological Response and PEPI Score Improves Long-term Prognostic Stratification in HR-positive Breast Cancer Following Neoadjuvant Endocrine Therapy

BACKGROUND/AIM: Neoadjuvant endocrine therapy (NET) is increasingly used in hormone receptor (HR)-positive breast cancer; however, optimal methods for predicting long-term outcomes remain limited. This study aimed to evaluate the prognostic value of pathological response and preoperative endocrine prognostic index (PEPI), and to assess whether their combination improves risk stratification. PATIENTS AND METHODS: A total of 160 postmenopausal patients with strongly HR-positive breast cancer (T1-3N0-1M0) treated with NET were retrospectively analyzed. Pathological response was assessed using the Miller & Payne grading system. PEPI scores were calculated based on post-treatment tumor characteristics. Survival outcomes, including relapse-free survival (RFS), distant disease-free survival (DDFS), and breast cancer-specific survival (BCSS), were analyzed. Patients with a PEPI score of 0-1 showed significantly better long-term outcomes compared to those with higher scores. Importantly, the combination of pathological response and PEPI demonstrated superior prognostic performance (78.1%) compared with either method alone. Patients identified as low-risk by the combined model exhibited excellent 10-year survival outcomes. CONCLUSION: The integration of pathological evaluation with PEPI scoring provides a simple and clinically applicable approach for prognostic stratification in HR-positive breast cancer following NET. This combined model may help identify patients who could safely avoid adjuvant chemotherapy, supporting individualized treatment strategies.