Pathological Response and Survival Outcomes Following Neoadjuvant Chemotherapy in HR+/HER2- Breast Cancer: Real-world Experience

Objective: Hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer (BC) is the most common subtype but shows limited sensitivity to neoadjuvant chemotherapy (NAC), and its clinical benefit remains controversial. This study evaluated clinicopathological characteristics, pathological response patterns, and survival outcomes in HR+/HER2- BC patients treated with NAC. Material and Methods: This retrospective cohort study included 186 women with stage II-III HR+/HER2- BC who received NAC followed by surgery between 2015 and 2024 at two tertiary centers. Pathological responses, event-free survival (EFS), and overall survival (OS) were analyzed. Logistic regression identified predictors of pathological complete response (pCR), and Cox models evaluated prognostic factors for survival. Results: After a median follow-up of 30.6 months, pCR was achieved in 13.4% of patients and 42.5% showed a partial pathological response, resulting in a total pathological response rate of 55.9%. Grade 3 tumors and estrogen receptor (ER) expression <90% independently predicted pCR. Five-year EFS and OS rates were 77% and 88%, respectively. High ER expression (≥90%) and any pathological response were strong independent predictors of improved EFS and OS, whereas pCR alone was not associated with survival. Conclusion: In HR+/HER2- BC treated with NAC, overall pathological response and ER expression provide greater prognostic value than pCR alone.