To determine whether lung tumors harboring mutated-EGFRs are more aggressive than those with WT-EGFR in terms of SBM occurrence, we used a median time interval between the diagnosis of lung cancer and the detection of SBM (MTSBM) as a surrogate of tumor aggressiveness. As shown in Table 4, the mutated-EGFR tumor had a significantly shorter MTSBM than the WT-EGFR one did (for all-stage disease, 31.6 months vs. not reached (NR), P of log-rank test = 0.043; for stage IIIB-IV disease, 23.5 months vs. NR, P = 0.017). As to stage IIIB-IV diseases with mutated-EGFRs, the L858R mutation-positive tumors had a slightly shorter MTSBM compared to the exon 19 deletion-positive ones (22.9 vs. 26.4 months, P = 0.743), but the difference was not statistically different.