Causal Relationship between Postoperative Recurrence and PD-L1 and EGFR Mutations in NSCLC: A Retrospective Cohort Study

Abstract Although information on the PD-L1 expression and EGFR mutations in non-small cell lung cancer (NSCLC) is important for determining therapeutic strategies, the causality between these two factors and postoperative recurrence and the association between each factor have remained unclear. We retrospectively assessed the PD-L1 expression and EGFR mutations in tumors of 280 NSCLC patients. The causality between the PD-L1 expression, EGFR mutations and postoperative recurrence were evaluated by a multivariate Cox proportional hazard analysis. The association between the PD-L1 expression and EGFR mutations was evaluated by a multinomial logistic regression analysis. The adjusted hazard ratio (HR) in cases with high (≥ 50%) PD-L1 expression was 4.83 (95% confidence interval [CI]: 1.51–15.5). The adjusted HRs in cases with EGFR major and minor mutations were 0.42 (95% CI: 0.14–1.25) and 0.63 (95% CI: 0.18–2.15), respectively. The high expression of PD-L1 (≥ 50%) was significantly associated with exon 21 L858R mutation (Ex21) of EGFR (adjusted odds ratio, 0.10; 95% CI, 0.01–0.87). The high expression of PD-L1 was an independent risk factor for postoperative recurrence in NSCLC, whereas EGFR mutations were not. The high expression of PD-L1 was negatively associated with Ex21. These findings may help identify NSCLC patients with an increased risk of postoperative recurrence.