EGFR and adenocarcinoma: Subsets of patients with adenocarcinoma and activating mutations within the kinase domain of the epidermal growth factor receptor (EGFR) gene have been successfully treated with selective tyrosine kinase inhibitors (TKIs), such as erlotinib, gefitinib, afatinib, and osimertinib, which are also characterized by reduced adverse events in comparison with traditional chemotherapy [6, 7].