Impact of platinum-based adjuvant chemotherapy on the effectiveness of IB-IIIA non-small cell lung adenocarcinoma with varying EGFR mutation statuses: a propensity score matching analysis

Background: Currently, targeted therapies are clinically applied to benefit patients with non-small cell lung cancer (NSCLC), including tyrosine kinase inhibitors (TKIs). However, most tumors inevitably develop resistance to these targeted drugs following treatment, leading to tumor progression or relapse. This study aimed to establish a theoretical basis for adjuvant therapy and further investigate whether platinum-based adjuvant chemotherapy can alleviate the current challenge of TKIs resistance in patients with epidermal growth factor receptor (EGFR) mutations. We retrospectively analyzed the prognostic efficacy of platinum-based adjuvant chemotherapy in patients with stage IB-IIIA non-small cell lung adenocarcinoma based on the mutation status of EGFR using propensity score matching (PSM) analysis. Methods: Among the 50 patients with non-small cell lung adenocarcinoma who underwent complete resection at the Guangzhou Institute of Cancer Research, the Affiliated Cancer Hospital, Guangzhou Medical University, from June 2014 to June 2018, there were 28 cases of wild-type EGFR (WT) and 22 cases of mutant EGFR (MT). PSM was employed to mitigate clinical feature bias between the WT and MT groups, thereby minimizing confounding effects on the results. The study analyzed 5-year disease-free survival (DFS) and 5-year overall survival (OS). Results: Univariate analysis identified smoking as the sole risk factor in the WT group [hazard ratio (HR), 4.963; 95% confidence interval (CI): 1.080-22.811; P=0.04]. No substantial risk factors pertinent to OS were identified in the MT group. Multivariate analysis shows that there were no significant risk factors related to OS in both the WT and MT groups, likely due to the small sample sizes. Prior to PSM, no significant differences in DFS (P=0.10, Cohen's d =0.41) or OS (P=0.17, Cohen's d =0.41) were noted between the WT and MT groups. Post-PSM analysis revealed a large effect size but no significant difference in DFS (P=0.13, Cohen's d=0.85), suggesting limited clinical relevance of this observed disparity. However, the OS was significantly better in the WT group compared to the MT group, with a substantial effect size (P=0.03, Cohen's d=1.46), meeting Cohen's threshold for clinically meaningful differences. Conclusions: Platinum-based adjuvant chemotherapy does not address the issue of targeted resistance and disease progression in patients with EGFR mutations.