Impact of platinum-free interval on the efficacy of platinum retreatment for recurrent non-small cell lung cancer after perioperative platinum-based chemotherapy: A multicenter retrospective study

ABSTRACT Background The role of platinum retreatment is unclear in patients with non-small cell lung cancer (NSCLC) who have postoperative recurrence after perioperative platinum-based chemotherapy. We investigated whether the platinum-free interval (PFI) is associated with progression-free survival (PFS) following platinum retreatment. Methods This multicenter retrospective cohort study included patients from four Japanese institutions who received platinum retreatment for postoperative recurrent NSCLC after prior perioperative platinum-based chemotherapy. PFS and overall survival (OS) were analyzed. The association between PFI and PFS was evaluated using Kaplan–Meier analysis and Cox regression and an optimal PFI cutoff was explored using maximally selected rank statistics. Results Thirty-one patients were included. Median PFS and OS after platinum retreatment were 7.6 months (95% CI, 5.9–16.9) and 30.6 months (95% CI, 18.6–not reached), respectively. PFS increased with longer PFI categories. A data-driven analysis suggested approximately 10 months as the optimal cutoff. Patients with PFI ≥10 months had significantly longer PFS than those with PFI <10 months (11.0 vs. 4.7 months; HR 0.35, 95% CI 0.15–0.83; p =0.01). In exploratory multivariable analysis, PFI ≥10 months and combination with immune checkpoint inhibitor therapy were independently associated with prolonged PFS. However, when PFI was analyzed as a continuous variable, the association did not reach statistical significance. Conclusion Longer PFI was associated with improved PFS after platinum retreatment in postoperative recurrent NSCLC in this cohort. The identified cutoff of approximately 10 months should be considered exploratory, however, and requires external validation.