The Correlation of PD-L1 Expression with Tumor Budding: Evaluating the Significance of Scoring Differences in Non-Small Cell Lung Cancer

Background: Tumor budding is a prognostic marker linked to epithelial–mesenchymal transition and the tumor microenvironment throughout various tumors. The programmed cell death protein 1 (PD-1) pathway functions as an important immune checkpoint that regulates lymphocyte activity within the tumor microenvironment. PD-1 ligand expression patterns may substantially affect the potential success of therapeutic blockade of this pathway. Methods: This study compares programmed cell death ligand 1 (PD-L1) expression with clinicopathological features using different scoring systems and assesses its prognostic value in patients with non-small cell lung cancer (NSCLC). Results: The study included 359 NSCLC cases. We found a statistically significant association between a negative combined positive score (CPS) or immune cell score (ICS) and advanced clinical stage and poor tumor differentiation. Moderate and high tumor budding scores correlated with positive PD-L1 expression across all three scoring systems. Overall survival (OS) revealed that PD-L1 positivity with ICS and CPS is a significant independent factor associated with a favorable prognosis. Kaplan–Meier analysis showed that CPS+ or ICS+ cases had significantly longer OS compared to CPS− or ICS− patients. In patients treated with immune checkpoint inhibitors, we observed no significant difference in OS between PD-L1-positive and PD-L1-negative cases across all scoring systems evaluated. Conclusion: Our study demonstrated a significant association between tumor budding in NSCLC and PD-L1 expression in tumor and immune cells. We showed that CPS or ICS positivity is a favorable prognostic factor for overall survival in patients with NSCLC.