The Prognostic Value of Dynamic Changes in Prognostic Nutritional Index (PNI) During Treatment in Lung Cancer: Is Improvement a Better Predictor than Baseline?

Objective Although the baseline Prognostic Nutritional Index (PNI) is a well known prognostic factor in lung cancer, the clinical significance of its fluctuation during treatment remains unclear. This study aimed to evaluate the prognostic value of dynamic changes in PNI and to determine whether improvement in nutritional-immune status correlates with survival outcomes. Methods A total of 478 patients diagnosed with lung cancer were retrospectively analyzed. PNI was calculated based on serum albumin and total lymphocyte counts. The baseline value was defined as PNI1, and the post treatment value as PNI2. The dynamic change in PNIΔ was categorized as increased, stable, or decreased. The relationship between these dynamic parameters and Overall Survival. and Progression Free Survival was assessed using Kaplan Meier and Cox regression analyses. Results The median follow up was 19.9 months. Patients with higher PNI1 and PNI2 scores exhibited significantly longer OS and PFS. Notably, patients who demonstrated an increase in PNIΔ during the treatment course had significantly longer overall survival compared to those with stable or decreased scores (p=0.023). In multivariate analysis, while cancer type and post treatment PNI (PNI2) were identified as independent prognostic factors (p=0.007 for PNI2), the dynamic improvement in PNI emerged as a critical indicator of better clinical trajectory in univariate analysis. Conclusion This study demonstrates that PNI is not merely a static baseline marker but a dynamic biomarker that reflects the host's response to treatment and disease. An increase in PNI values during treatment is associated with improved survival, suggesting that dynamic monitoring of nutritional and immune status provides valuable prognostic information for patient management in lung cancer.