With the use of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs), the earliest molecular targeted agents introduced in lung cancer, re-biopsy of resistant lesions has become popular with the aim of identifying emerging EGFR T790M as a resistance mutation to first- and second-generation EGFR-TKIs [15, 16]. This evidence concerns the gene EGFR and lung cancer.