Abstract
An 80-year-old man underwent a left lower lobectomy for lung adenocarcinoma. Next-generation sequencing in a clinical trial identified an epidermal growth factor receptor (EGFR) exon 19 insertion (exon19ins), which was not detected by the Oncomine™ Dx Target Test®, a companion diagnostic tool for EGFR mutations. However, the Lung Cancer Compact Panel® Dx (LCCP), another companion diagnostic tool, confirmed exon19ins. Osimertinib was administered, which led to a slight tumor response. This case suggests that LCCP may be useful in detecting rare EGFR mutations and that osimertinib may be effective against exon19ins.