Epidermal growth factor receptor-tyrosine kinase inhibitor therapy is especially beneficial to patients with exon 19 deletion compared with exon 21 L858R mutation in non-small-cell lung cancer: Systematic review and meta analysis

Background: The correlation between epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) and EGFR sensitive mutation subtypes in advanced or metastatic non-small cell lung cancer (NSCLC) remains uncertain. We performed this meta-analysis to determine different clinical outcomes between patients with exon 19 deletion accepting EGFR-TKI therapy compared with those with exon 21 L858R mutation. Methods: PubMed and Web of Science were analyzed for eligible trials. Raw data were extracted to give pooled estimates of the effect of EGFR-TKI therapy on objective response rate (ORR), one-year progression-free survival (PFS), and two-year overall survival (OS). Results: We identified 13 eligible trials involving 912 patients. Prospective meta-analysis demonstrated that the ORR of the 19 deletion group was significantly higher than the 21 L858R mutation group (odds ratio [OR] 1.98, 95% confidence interval [CI] 1.18-3.33; P = 0.01), but no statistical significance between the one-year PFS rate of the 19 deletion and 21 L858R groups (OR 1.44, 95% CI 0.96-2.18; P = 0.08) was found. However, retrospective meta-analysis demonstrated that a significantly higher one-year PFS rate was associated with the 19 deletion group (OR 1.73,95% CI 1.17-2.56; P = 0.006). The two-year survival rate of the 19 deletion group was significantly higher than the 21 L858R group (OR 5.27, 95% CI 1.76-15.71; P = 0.003). Conclusions: In advanced NSCLC patients, an exon 19 deleton may provide superior ORR, PFS, and OS after EGFR-TKI treatment compared with an exon 21 L858R mutation.