Results: Among the 4,377 patients who met the study criteria, median age was 73 yrs; 64% were female; and 25% current/former smokers. Among the 3,342 patients identified in Period 1, the most commonly prescribed first-line EGFR-TKI was gefitinib 46% (1,548 patients), followed by afatinib 29% (985 patients), and erlotinib 23% (770 patients). A variety of treatment sequence patterns (total 834 patterns) were observed among which single line only was 45.15% (1,509 patients), two lines 24.3% (812 patients), and three or more lines 30.55% (1,021 patients). In Period 2 (total 1,035 patients), the most commonly prescribed first-line EGFR-TKI was osimertinib 84% (872 patients), followed by gefitinib 8.1% (84 patients), afatinib 5.3% (55 patients), and erlotinib 2.3% (24 patients). For Period 1, mDOT of one line of therapy was 335 days, that of two lines was 501.5 days, and three lines was 571.5 days. Among patients receiving two lines of treatment, EGFR-TKI sequences and their mDOT were: 1G01G, 15% (122 patients), 396 days; 1G02G, 6.5% (53 patients), 483 days; 1G03G, 37% (301 patients), 584 days; 2G01G, 4.8% (39 patients), 409 days; 2G03G, 13.7% (111 patients), 612 days. Conclusion: Periods before and after first-line indication of osimertinib showed large differences in the choice of EGFR-TKI prescribed in first-line and variety of sequence patterns. In Period 1, patients receiving treatment sequence of 1G or 2G EGFR-TKI followed by osimertinib showed long-term survival benefit in real world. Treatment sequences in Period 2 remain to be analyzed after accumulation of dataset.