BACKGROUND: To elucidate the clinical, pathologic, and prognostic impacts of epidermal growth factor receptor (EGFR) mutation and mutation subtypes in early-stage lung cancer, the study investigators conducted a retrospective analysis of the Japanese Joint Committee of Lung Cancer Registry database (a nationwide database for patients with surgically resected lung cancer; n = 18,973). METHODS: Of 13,951 patients classified as having nonsquamous non-small cell lung cancer in the database, 5780 patients (41.0%) had been tested for an EGFR mutation and were included in this study. RESULTS: An EGFR mutation was detected in 2410 patients (41.7%), and the presence of an EGFR mutation was significantly correlated with clinicopathologic factors such as the presence of ground-glass opacity (P < .001) and better prognosis. Analysis of initial recurrence sites identified significantly higher frequencies of brain and adrenal gland metastases in patients with and without an EGFR mutation, respectively. Of 2410 patients with EGFR mutations, 983 (40.8%) had an exon 19 deletion (Exon 19 Del), 1170 (48.5%) had an L858R mutation, and 257 (10.7%) had other EGFR mutations. A higher smoking rate was found in patients with other EGFR mutations (P = .02). In the comparison of Exon 19 Del and L858R, we found that Exon 19 Del correlated with younger age (P < .001), a higher rate of pure solid tumors (P < .001), advanced pathologic stage (trend P < .001), and poorer recurrence-free survival (P = .001). CONCLUSIONS: In addition to the clinicopathologic and prognostic impacts of EGFR mutation status, tumors with Exon 19 Del have a more aggressive phenotype and patients have a poorer prognosis than with L858R in early-stage lung cancers.