The combination of PD-L1 expression and the neutrophil-to-lymphocyte ratio as a prognostic factor of postoperative recurrence in non-small-cell lung cancer: a retrospective cohort study

Background While PD-L1 expression and neutrophil-to-lymphocyte ratio (NLR) are prognostic biomarkers for lung cancer, few studies have considered their interaction. We hypothesized that the product of PD-L1 expression (tumor proportion score) and the NLR (PD-L1 × NLR) might be a postoperative prognostic marker reflecting the immune microenvironment of lung cancer. Methods We analyzed the association between PD-L1 × NLR and postoperative recurrence-free survival in 647 patients with NSCLC using multivariable Cox proportional hazards models. Results In the analysis of PD-L1 × NLR as a categorical variable, the group with PD-L1 × NLR ≥ 25.8 had a significantly higher hazard ratio (HR) than the group with < 25.8 (adjusted HR 1.78, 95% confidence interval [CI] 1.23–2.60). The adjusted HR for PD-L1 × NLR, considered a continuous variable, was 1.004 (95% CI, 1.002–1.006). The risk of postoperative recurrence increased by 1.004-fold for each unit increase in PD-L1 × NLR, and a more than 2-fold increase in risk was observed for values ≥ 170. Conclusions PD-L1 × NLR may be used in real-world clinical practice as a novel factor for predicting the risk of postoperative recurrence after lung cancer surgery.