EGFR and lung cancer: However, the inability to obtain primary tumor tissues, particularly through repeated biopsies, from patients with advanced-stage lung cancer makes the use of a serum proteomic classifier for analysis of EGFR gene mutation status clinically important given the high sensitivity (84.6%) of the technique and the favorable response to EGFR-TKIs in patients whose matched samples were labeled as “mutant” by the serum proteomic classifier.