EGFR Exon 20 Insertion Mutations: CT Characteristics and Clinicopathologic Features in Non-Small Cell Lung Cancer

Background: Epidermal growth factor receptor gene (EGFR) exon 20 insertion (ex20-ins) mutations are a rare and heterogeneous type of non-small cell lung cancer (NSCLC), with a prevalence of approximately 1.5-2.5%. The differences between computed tomography (CT) characteristics and clinical pathology of EGFR ex20-ins mutant NSCLC patients and classical EGFR mutant ones remain to be evaluated. Method: A retrospective study of 1432 EGFR-positive patients in three medical centers was conducted to analyze the frequency and genetic features, CT characteristics, and clinical pathology data of EGFR ex20-ins mutations. Result: Among the EGFR-positive NSCLC patients, 1.75% (25/1432) had EGFR ex20-ins mutations. Compared with classical mutations, ex20-ins patients had more solid components (50%) and a lower proportion of the lepidic subtype (35.7%) in pathological subtypes, and the most common mutation type is p.V769_D770insASV (4/25). Conclusion: Although EGFR ex20-ins mutations have similarities with classical EGFR mutations, our study still finds differences between them in clinical pathology, CT characteristics, and other aspects.