Prognostic Significance of the CALM Index in Surgically Resected Non-Small Cell Lung Cancer.

Background: Anatomical staging is often insufficient for predicting outcomes in stage I-IIIA non-small cell lung cancer (NSCLC) patients after curative resection due to inherent prognostic variability. In this study, we evaluated the prognostic value of the C-reactive protein-albumin-lymphocyte-monocyte (CALM) index as an integrative biomarker for overall survival (OS). Methods: This retrospective study included 533 patients with stage I-IIIA NSCLC. We assessed the association between the CALM index and OS using multivariable Cox proportional hazards models, adjusted for established clinicopathological factors. We employed LASSO-penalized regression to optimize variable selection and ensure model stability. Comprehensive performance metrics were calculated, including Harrell's C-index, integrated area under the curve (iAUC), integrated discrimination improvement (IDI), and decision-curve analysis (DCA). Results: The CALM index was identified as a stable, independent predictor of OS across both conventional and LASSO-penalized models. The final multivariable model incorporated the CALM index alongside age, pathological stage, American Society of Anesthesiologists status, pleural invasion, and the modified Shine-Lal index. Incorporation of the CALM index significantly enhanced model discrimination and risk reclassification at 3 and 5 years, while consistently increasing net clinical benefit across a wide range of threshold probabilities. Conclusions: The CALM index is a biologically plausible, robust, and readily accessible prognostic biomarker that provides incremental prognostic information beyond established factors in patients with resected stage I-IIIA NSCLC. Its integration into postoperative assessment offers a framework for refined prognostic stratification and more individualized clinical decision-making.