Background: North East Japan Study Group (NEJ) 005/ Tokyo Cooperative Oncology Group (TCOG) 0902 study has demonstrated that first-line concurrent (C) and sequential alternating (S) combination therapies of EGFRtyrosine kinase inhibitor (gefitinib) plus platinum-based doublet chemotherapy (carboplatin/pemetrexed) offer promising efficacy with predictable toxicities for patients with EGFR-mutant NSCLC (ASCO2014, Ann Oncol 2015). However, overall survival (OS) data were insufficient because of the lack of death events in the primary report. Methods: Progression-free survival (PFS) and OS were re-evaluated at the final data cutoff point (November 2016) for the entire population (N = 80). Results: At the median follow-up time of 35.6 months, 88.8% of patients had progressive disease and 72.5% of patients had died. Median PFS was 17.5 months for the C regimen and 15.3 months for the S regimen (p = 0.13). Median OS time was 43.3 with the C regimen and 30.7 months with the S regimen (p = 0.018). Updated response rates were similar in both groups (90.2% and 82.1%, respectively; p = 0.34). Patients who had common mutations showed no significant differences in PFS according to type of mutation. Patients with Del19 displayed relatively better OS (median: 45.3 and 33.3 months for C and S regimens) than those with L858R (31.4 and 28.9 months). No severe adverse events including interstitial lung disease have occurred during the follow-up period since the primary report. Conclusions: This updated analysis has confirmed that PFS is improved with first-line combination therapies compared to that with gefitinib monotherapy, and the C regimen in particular offers an overall survival benefit of 43 months in the EGFR-mutated setting. Our on-going NEJ009 study will clarify whether this combinational strategy can be incorporated into routine clinical practice. Clinical trial information: UMIN000002789.