Molecular alterations and clinical prognostic factors in resectable non-small cell lung cancer.

Background: EGFR inhibitor and immunotherapy have been approved for adjuvant treatment in resectable non-small cell lung cancer (NSCLC). Limited reports of molecular and clinical characteristics as prognostic factors in NSCLC have been published.

Methods: Medical records of patients with resectable NSCLC stage I-III diagnosed during 2015-2020 were reviewed. Real time-PCR (RT-PCR) was performed for EGFR mutations (EGFRm). Immunohistochemistry staining was conducted for ALK and PD-L1 expression. Categorical variables were compared using chi-square test and Fisher's exact test. Survival analysis was done by cox-regression method.

Results: Total 441 patients were included. The prevalence of EGFRm, ALK fusion, and PD-L1 expression were 57.8%, 1.9%, and 20.5% (SP263), respectively. The most common EGFRm were Del19 (43%) and L858R (41%). There was no significant difference of recurrence free survival (RFS) by EGFRm status whereas patients with PD-L1 expression (PD-L1 positive patients) had lower RFS compared to without PD-L1 expression (PD-L1 negative patients) (HR = 1.75, P = 0.036). Patients with both EGFRm and PD-L1 expression had worse RFS compared with EGFRm and PD-L1 negative patients (HR = 3.38, P = 0.001). Multivariable analysis showed higher CEA at cut-off 3.8 ng/ml, pT4, pN2, pStage II, and margin were significant poor prognostic factors for RFS in the overall population, which was similar to EGFRm population (exception of pT and pStage). Only pStage was a significant poor prognostic factor for PD-L1 positive patients. The predictive score for predicting of recurrence were 6 for all population (63% sensitivity and 86% specificity) and 5 for EGFRm population (62% sensitivity and 93% specificity).

Conclusion: The prevalence and types of EGFRm were similar between early stage and advanced stage NSCLC. While lower prevalence of PD-L1 expression was found in early stage disease. Patients with both EGFRm and PD-L1 expression had poorer outcome. Thus PD-L1 expression would be one of the prognostic factor in EGFRm patients. Validation of the predictive score should be performed in a larger cohort.