Neutrophil Percentage-to-Albumin Ratio as a Prognostic and Predictive Biomarker in Non-Metastatic Breast Cancer Treated with Neoadjuvant Chemotherapy: Findings from a Retrospective Cohort

Background/Objectives: This study aimed to investigate the prognostic and predictive significance of the pretreatment neutrophil percentage-to-albumin ratio (NPAR) in patients with non-metastatic breast cancer. NPAR is a composite biomarker reflecting both systemic inflammatory activity and nutritional status. Its association with treatment response and survival outcomes in patients receiving neoadjuvant chemotherapy was evaluated. Methods: This retrospective observational study included 194 patients diagnosed with non-metastatic breast cancer who underwent neoadjuvant chemotherapy between 2004 and 2024. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal NPAR cut-off value. Patients were categorized into low-NPAR (n = 150) and high-NPAR (n = 44) groups. Results: Clinicopathological characteristics were comparable between the groups. However, patients with elevated NPAR values demonstrated poorer treatment responses. The objective response rate was significantly lower in the high-NPAR group compared to the low-NPAR group (70% vs. 87%). In addition, progressive disease occurred more frequently in patients with high NPAR values (16% vs. 5%). Survival analysis revealed markedly worse outcomes among patients with elevated NPAR. Multivariate Cox regression analysis confirmed high NPAR as an independent predictor of reduced overall survival (HR: 3.79; 95% CI: 1.68–8.80). Conclusions: Elevated pretreatment NPAR values are associated with inferior response to neoadjuvant chemotherapy and unfavorable long-term survival outcomes. NPAR may serve as a simple and cost-effective biomarker for risk stratification and could assist clinicians in identifying patients who may benefit from more individualized therapeutic strategies.