Do Inflammatory Indices Predict Neoadjuvant Chemotherapy Response in Hormone Receptor-positive, HER2-negative Breast Cancer?

Aim: The aim of this study was to evaluate clinical, pathological, and inflammatory markers that can predict pathological complete response (pCR) after neoadjuvant chemotherapy (NACT) in patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2 (HER2) HER2breast cancer. Materials and Methods:A retrospective analysis was conducted on 109 patients aged 18-80 years with HR+/HER2-breast cancer who underwent NACT at University of Health Sciences Türkiye, Balıkesir Atatürk City Hospital between January 1, 2020, and May 1, 2025.All patients received standard anthracycline-taxane-based chemotherapy.Pre-treatment blood tests were used to calculate the neutrophil-to-lymphocyte ratio (NLR), platelet-tolymphocyte ratio (PLR), and systemic immune-inflammation index (SII).pCR was defined as the absence of residual invasive tumor in the breast and axillary lymph nodes.Factors affecting pCR were evaluated using logistic regression analysis.Results: pCR was achieved in 21.1% of patients.Most of the pCR group was under 50 years of age and had the luminal B subtype.ROC analysis showed that NLR, PLR, and SII were not significant predictors of pCR (p>0.05).In univariate analysis, luminal B subtype, low estrogen receptor (ER) levels, high Ki-67, and high tumor grade were significantly associated with pCR.In multivariate analysis, only low ER levels and high Ki-67 remained independent predictors. Conclusion:Inflammatory markers are insufficient to predict pCR in HR+/HER2-breast cancer.Low ER levels and high Ki-67 are associated with a better response to NACT.The findings highlight the importance of biomarkers in personalizing treatment response.