Association Between Neutrophil Percentage-to-Albumin Ratio (NPAR) and the Prognosis of Non-Small-Cell Lung Cancer

Objective: This study investigates the prognostic value and clinical utility of the neutrophil percentage-to-albumin ratio (NPAR) in patients with resected non-small-cell lung cancer (NSCLC). Methods: We retrospectively included 335 patients with NSCLC who underwent lung resection at our institution between January 2017 and October 2018. Optimal cutoffs for preoperative and postoperative day 1 (D1) NPAR were determined using X-tile (version 3.6.1; Yale University, New Haven, CT, USA) to define high and low groups. Overall survival (OS) was evaluated using Kaplan-Meier analysis and Cox proportional hazards models. A perioperative NPAR trajectory (low-low, low-high, high-low, high-high) was constructed to characterize dynamic risk patterns. To mitigate potential bias associated with postoperative measurements, a D1 landmark analysis was performed. A nomogram was developed based on the multivariable model and assessed by calibration at 1, 3, and 5 years. Incremental clinical value beyond TNM stage and surgical approach was evaluated using decision curve analysis (DCA), as well as by 5-year continuous net reclassification improvement (NRI) and integrated discrimination improvement (IDI). Results: The optimal cutoffs for preoperative and postoperative D1 NPAR were 14.5 and 23.1, respectively. In univariate analyses, sex, smoking history, preoperative NPAR, postoperative D1 NPAR, pathologic type, TNM stage, surgical approach, and adjuvant therapy were associated with OS (all p < 0.01). In multivariable Cox regression, high preoperative NPAR (HR 1.896, 95% CI 1.135-3.168; p = 0.014) and high postoperative D1 NPAR (HR 1.905, 95% CI 1.097-3.305; p = 0.014) were independent risk factors, along with TNM stage (Stage II: HR 2.824, 95% CI 1.209-6.595; p = 0.016; Stage III: HR 9.470, 95% CI 4.935-18.171; p < 0.001) and open surgery (HR 2.350, 95% CI 1.341-4.117; p = 0.003). Trajectory analysis further stratified risk, with the high-high group showing the poorest survival (adjusted HR 3.48, 95% CI 1.43-8.47; p = 0.006). The association of postoperative NPAR persisted in the D1 landmark analysis (HR 1.836, 95% CI 1.071-3.148; p = 0.027). Adding NPAR to TNM stage and surgical approach improved 5-year risk reclassification (continuous NRI 0.377, 95% CI 0.094-0.659; IDI 0.028, 95% CI -0.002-0.054) and increased net benefit on DCA. The nomogram demonstrated acceptable calibration at 1, 3, and 5 years. Conclusions: This study demonstrates that NPAR serves as an independent prognostic marker for long-term outcomes in patients with NSCLC. The use of NPAR offers clinicians a comprehensive and precise tool for assessing patient prognosis.