Albumin–Neutrophil Composite Grading (ANPG) for Predicting Overall Survival in Colorectal Cancer: A Retrospective Cohort Study

Background: Inflammatory responses and nutritional status are critical determinants of colorectal cancer (CRC) progression and clinical outcomes. This study aimed to evaluate the prognostic value of a novel albumin-neutrophil composite grading (ANPG) system and to develop a nomogram for predicting overall survival (OS) in CRC patients following curative resection. Methods: A retrospective analysis was conducted on 660 consecutive patients with primary CRC who underwent R0 resection between December 2017 and December 2018. The ANPG was constructed based on preoperative serum albumin levels and neutrophil counts, with optimal cutoff values determined by receiver operating characteristic (ROC) curve analysis. Prognostic factors were identified using univariate and multivariate Cox proportional hazards regression models. A predictive nomogram was developed and internally validated via bootstrap resampling (800 iterations) and time-dependent ROC analysis. Decision curve analysis (DCA) was performed to assess clinical utility. Results: The median follow-up duration was 2442 days (interquartile range: 2117–2537 days), during which 108 cancer-specific deaths occurred. The ANPG demonstrated superior discriminative ability (area under the curve [AUC] = 0.637, 95% confidence interval [CI]: 0.588–0.687, P < 0.001) compared to established inflammatory and nutritional markers, including the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), fibrinogen-to-albumin ratio (FAR), and fibrinogen-neutrophil-lymphocyte ratio (F-NLR). Kaplan-Meier survival analysis revealed significant differences in OS across ANPG grades (Log-rank χ² = 24.423, P < 0.001), with 5-year OS rates of 93.7%, 83.2%, and 74.4% for grades 0, 1, and 2, respectively. Multivariate Cox regression analysis identified ANPG (grade 1 vs. 0: hazard ratio [HR] = 2.190, P = 0.020; grade 2 vs. 0: HR = 3.256, P < 0.001), age (HR = 1.032, P < 0.001), carbohydrate antigen 19-9 (CA19-9) (HR = 1.002, P = 0.003), histological type (HR = 1.954, P = 0.005), and TNM stage as independent prognostic factors. The nomogram incorporating these variables—retaining carcinoembryonic antigen due to its clinical relevance and contribution to model performance—achieved a concordance index (C-index) of 0.806 (95% CI: 0.788–0.824) with excellent calibration, significantly outperforming TNM staging alone in predictive accuracy. Decision curve analysis (DCA) showed greater net benefit across a wide range of threshold probabilities for 5-year OS compared to TNM staging, confirming its enhanced clinical applicability. Conclusions: The ANPG is a robust and independent prognostic indicator in CRC patients undergoing curative resection. The developed nomogram provides a clinically valuable tool for individualized survival prediction and risk stratification.