Post-Progression Survival Is Strongly Associated with Overall Survival in Patients Exhibiting Postoperative Relapse of Non-Small-Cell Lung Cancer Harboring Sensitizing EGFR Mutations

Background and Objective: Patients with advanced non-small-cell lung cancer (NSCLC) harboring sensitizing epidermal growth factor receptor (EGFR) mutations show a good response to EGFR-tyrosine kinase inhibitors (EGFR-TKIs). The subsequent treatments influence the evaluability of the efficacy of front-line therapy on overall survival (OS). Consequently, we evaluated the associations of relapse-free survival (RFS) and post-progression survival (PPS) with OS in patients who exhibited postoperative relapse of EGFR-mutated NSCLC. Materials and Methods: We analyzed the data of 35 patients with EGFR-mutated NSCLC who underwent complete resection between January 2007 and June 2019. The correlations of RFS and PPS with OS were evaluated at the individual patient level. Results: Linear regression and Spearman’s rank correlation analyses demonstrated that the PPS highly correlated with OS (r = 0.91, p < 0.05, R(2) = 0.85), whereas the RFS weakly associated with OS (r = 0.36, p < 0.05, R(2) = 0.25). Age and performance status at relapse were significantly associated with PPS. Conclusion: Overall, PPS was more strongly and significantly associated with OS than RFS. These results suggest that the OS of our cohort may be affected by treatments, besides postoperative relapse. However, larger-scale prospective studies are needed to confirm these results.