Letter to the editor concerning first-line therapy with afatinib – an irreversible EGFR TKI and overall survival of NSCLC patients with EGFR gene mutations - Krawczyk, Paweł; Powrózek, Tomasz; Nicoś, Marcin; Milanowski, Janusz (Contemporary Oncology/Współczesna Onkologia, 2015)