The European Society of Medical Oncology (ESMO) recommends upfront HER2 mutation testing (preferentially sequencing of exon 20) as part of a larger routine testing panel using next-generation sequencing (NGS), in patients with unresectable stage III and IV NSCLC who meet two or three of the following criteria, (i) lung adenocarcinoma or adenosquamous carcinoma; (ii) never-smoker status; (iii) female [4]. Here, ERBB2 is linked to lung adenocarcinoma.