Epidermal Growth Factor Receptor Exon 20 Insertion in Early Resected Non-Small Cell Lung Cancer: A Retrospective, Single-Center Study in Taiwan.

[BACKGROUND] exon 20 insertions account for 1% to 10% of mutations in non-small-cell lung cancer (NSCLC) and are known to confer resistance to traditional tyrosine kinase inhibitors. However, the prognostic significance of these mutations in early-stage resected NSCLC remains unclear. This study assesses outcomes in patients with resected NSCLC harboring exon 20 insertions, comparing them to patients with common mutations and those with wild-type .

[METHODS] We retrospectively reviewed 3,235 patients who underwent resection for NSCLC at Tri-Service Hospital between 2008 and 2021. After excluding cases lacking testing, incomplete data, or advanced-stage disease, 44 patients with exon 20 insertions were matched to 602 patients with common mutations and 729 with wild-type . Clinical characteristics, disease-free survival (DFS), and overall survival (OS) were analyzed using the Kaplan-Meier method, with statistical comparisons performed using the log-rank test. Cox proportional hazards models were used to identify independent prognostic factors.

[RESULTS] Patients with exon 20 insertions were younger and more frequently presented with stage IA disease. The 5-year DFS was 79% in the exon 20 insertion group, compared to 81% in the common mutation group and 83.9% in the wild-type group. The 5-year OS was 78.5% for exon 20, 91.9% for common mutations, and 91% for wild-type. While no significant differences in DFS or OS were observed between groups, the exon 20 insertion group had a higher incidence of secondary cancers. Multivariable analysis indicated that exon 20 insertion was independently associated with worse OS, but not with DFS.

[CONCLUSION] exon 20 insertions do not significantly shorten DFS, but are associated with inferior OS in early-stage resected NSCLC. Given the limited treatment options, the role of adjuvant therapy warrants further investigation.