Prognostic Value of Dynamic Changes in Immune-Inflammatory and Tumor Biomarkers Following Chemoradiotherapy in Locally Advanced Rectal Cancer

Background: The prognostic utility of inflammatory and tumor biomarkers, including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and carcinoembryonic antigen (CEA), in rectal cancer has been increasingly studied, but results remain inconsistent. This study evaluates the prognostic significance of pre- and post-chemoradiotherapy (CRT) levels and dynamic changes in NLR, PLR, and CEA for predicting overall survival (OS) and disease-free survival (DFS) in locally advanced rectal cancer (LARC). Methods: This retrospective study included 261 LARC patients treated with neoadjuvant CRT followed by curative surgery. Pre- and post-CRT NLR, PLR, and CEA were collected. Survival analyses were performed using Kaplan–Meier curves and Cox proportional hazards models. ROC curves assessed predictive performance, and patients were stratified by cut-offs and biomarker changes (delta values). Results: The cohort had a mean age of 55.5 years; 55.9% were male, and 93.5% had clinical stage III disease. Post-CRT NLR (HR: 1.05, p = 0.007) and CEA (HR: 1.00, p < 0.001) were independently associated with OS, while post-CRT CEA and AJCC stage III were predictors of DFS (HR: 4.12, p = 0.009). ROC analysis showed improved accuracy when combining NLR (AUC = 0.66) and CEA (AUC = 0.70), yielding a combined AUC of 0.84 for OS. Patients with decreases in both NLR and CEA had the most favorable outcomes, whereas increases in both markers indicated poor prognosis (OS p < 0.0001; DFS p = 0.00019). Conclusions: Post-CRT levels and dynamic changes in NLR and CEA are independent prognostic markers in rectal cancer. Their combined assessment enhances survival prediction and may guide personalized postoperative surveillance and treatment strategies.