EGFR and non-small cell lung carcinoma: A meta-analysis that included patients with advanced NSCLC treated with EGFR-TKIs as first-line therapy was recently conducted [20], with a total of 872 patients with exon 19 deletions and 686 patients with exon 21 L858R substitutions being enrolled, showing that treatment with EGFR-TKIs improves PFS by approximately 50% in those with exon 19 deletions compared to those with exon 21 substitutions.