This retrospective study aimed at evaluating the prognostic impact of high serum levels of either the HER-2 extracellular domain (ECD) or the epidermal growth factor receptor (EGFR) ECD measured using two specific ELISAs in 221 patients with non-small-cell lung cancer (NSCLC) receiving conventional therapy and 41 nonmalignant pulmonary diseases patients. Here, EGFR is linked to lung disorder.