ERBB2 and adenocarcinoma: Focusing on adenocarcinoma, the main NSCLC subtype (50%), more than half of the cases are driven by recognized oncogenic alterations, such as epidermal growth factor receptor (EGFR), Kirsten rat sarcoma viral oncogene homolog (KRAS), Echinoderm Microtubule-associated protein-like protein 4 fused to anaplastic lymphoma kinase (EML4-ALK), mesenchymal-epithelial transition (MET) factor, serine/threonine-protein kinase B-Raf (BRAF) or human epidermal growth factor 2 (HER2/ErbB2/neu) [6,7].