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

Abstract Background While PD-L1 expression and the 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 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 non-small cell lung cancer patients 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 1.004-fold for each unit increase in PD-L1×NLR, and a more than 2-fold increase in risk was observed for values of ≥ 170. Conclusions The PD-L1×NLR may be used in real-world clinical practice as a novel factor to predict the risk of postoperative recurrence after lung cancer surgery.