Prevalence of EGFR gene mutations in patients with early-stage resectable non-small cell lung cancer in Spain: the ORIGEN study

Background: Geographic variability in epidermal growth factor receptor (EGFR) mutation rates in early-stage non-small cell lung cancer (NSCLC) has been reported. However, the frequency of EGFR mutations in patients with early-stage resected NSCLC in Spain has not been previously investigated. We aimed to determine the prevalence of EGFR mutations in patients with early-stage resected NSCLC in Spain. Methods: This was an observational, multicenter, cross-sectional study. Sensitizing EGFR mutations were assessed via real-time polymerase chain reaction (PCR)-based molecular analysis with the IdyllaTM TM EGFR Mutation Test , next-generation sequencing (NGS) analysis with the OncomineTM TM Precision Assay. Results: A total of 172 patients with surgically resected non-squamous NSCLC were analysed. Median age was 67.5 years , 57.6% were male, 96.5% had adenocarcinoma histology and 65% had stage IA/IB. EGFR mutations were found using IdyllaTM TM EGFR Mutation Test in 25 patients out of 172 patients (14.5%), which consisted of exon 19 deletion in 13 patients (7.6%), exon 21 L858R point mutation in 11 (6.4%), and exon 20 mutation (T790M) in 1 (0.6%) patient. The OncomineTM TM test was conducted in 128 patients, which detected exon 19 deletions in 10 patients (7.8%), exon 21 mutations in 10 patients (7.8%), and exon 20 insertions in 5 (3.9%) patients. The OncomineTM TM test was able to detect concurrent mutations in tumor suppressor genes ( TP53, PI3KCA, CDKN2A, PTEN) ) and another actionable alteration beyond EGFR, , such as mutations in KRAS G12C (22%), ERBB2 (6%), METex14 (2%), BRAF V600E (2%) and ALK and ROS1 fusions (2%, each). Conclusions: The prevalence of EGFR mutations in early stage (IA-IIIB), resectable, non-squamous NSCLC observed in our study is consistent with that reported in advanced NSCLC in Spain. Molecular testing is crucial in early-stage NSCLC and can be performed either with single-gene testing or NGS.