Radiological features in relation to epidermal growth factor receptor mutation status of exon 19 and 21 in lung adenocarcinoma

ABSTRACT Introduction: Exon 19 and exon 21 subtypes account for 90% of epidermal growth factor receptor (EGFR)-positive lung adenocarcinoma cases. Tyrosine kinase inhibitors (TKIs) provide a higher response rate in EGFR-positive subtypes. Hence, the study of clinical and radiological features related to exon 19 and 21 helps as a clinical predictor in patients with inoperable lung cancer. Aim: To identify the computed tomography (CT) features associated with EGFR mutation subtypes, exon 19 and exon 21, in lung adenocarcinoma patients. Materials and Methods: This was a cross-sectional study involving 117 patients who underwent contrast-enhanced CT (CECT) and were found to have EGFR-negative subtype, exon 19, and exon 21 status of EGFR-positive lung adenocarcinoma, from March 2021 to June 2022. Results: CT features that have a higher correlativity with the exon 19 subtype of EGFR-positive mutation of lung adenocarcinoma include the presence of air bronchogram, presence of necrosis, intralesional calcifications, and intralesional vacuole sign. Radiological and clinical features that favor the exon 21 subtypes of EGFR-positive mutation of lung adenocarcinoma include non-smoking, spiculated margins, presence of ground glass opacities (GGOs), subsolid density, and satellite nodules. Conclusion: Different CT and clinical features are present between the EGFR-wild type and EGFR-mutated subtypes in exon 19 and exon 21. Clinicoradiological findings can serve as a reliable indicator for detecting the EGFR mutation status in lung adenocarcinoma and predicting exon 19-positive and exon 21-positive mutation subtypes.