Prognostic Factors in Japanese EGFR Mutation-Positive Non-Small-Cell Lung Cancer: A Real-World Single-Center Retrospective Cohort Study

Background The prognosis of patients with epidermal growth factor receptor (EGFR) mutation-positive lung cancer has improved significantly since the advent of EGFR tyrosine kinase inhibitors (EGFR-TKIs). We aimed to investigate the relationship between patient characteristics, EGFR genotype, therapeutic agents, and the prognosis of the patients with EGFR mutation-positive lung cancer. Methods This retrospective cohort study analyzed 198 Japanese patients with unresectable EGFR mutation-positive lung cancer who were treated with EGFR-TKIs at Toho University Sakura Medical Center from April 2006 to December 2021. Factors associated with overall survival (OS) were analyzed using Cox proportional hazards analysis. Results Patients who received osimertinib had a significantly longer OS than did those not receiving it (median OS, 36.2 versus 20.7 months; p < 0.001).There were significant differences in OS between patients with EGFR mutation who received osimertinib as first-line treatment, T790M-positive patients who received osimertinib as second- or later-line treatment, and those who did not receive it (median OS, 28.2 versus 40.2 versus 20.7 months; p = 0.003). However, in T790M-negative patients, no significant difference in OS was noted between those who did and did not receive osimertinib as post-treatment (median OS, 28.0 versus 40.0 months; p = 0.619). Multivariate Cox proportional hazards analysis showed that osimertinib treatment was associated with longer OS (hazard ratio, 0.480; 95% confidence interval, 0.326-0.707; p < 0.001). Conclusion The patients who were T790M-positive in the first-line treatment with first or second-generation EGFR-TKIs and were given osimertinib as the second or later line treatment had a better prognosis than the patients who were T790M-negative in the first-line treatment with first or second-generation EGFR-TKIs and could not receive osimertinib.