Patients with an exon 19 deletion have longer survival compared to those with an L858R mutation [8–10], theoretically implying that more BM would be observed throughout the disease course of the former. One report supported this expectation (38.2% vs. 25.6%, P = 0.016) , but another  and our data did not, regarding the overall BM in the patients of all-stage disease. Our analysis further showed that the cumulative incidence of SBM in stage IIIB-IV NSCLC was similar between the EGFR exon 19 deletion-positive and the L858R mutation-positive groups (39.5%, vs. 34.5%), although the former exhibited a slightly longer OS (20.6 vs. 14.2 months). This finding may be partially explained by the observations that the L858R mutation-positive tumors had an inferior disease control rate to EGFR-TKIs as first-line treatment (63.6% vs. 100%, P of chi-square test = 0.017, table not shown).