Purpose: This study aimed to explore the clinical value of SBRT for primary lung lesions of EGFR-mutant NSCLC patients with non-oligometastatic disease during first-line EGFR-TKI treatment.
Methods: We identified patients with stage IV EGFR-mutant non-oligometastatic NSCLC who were suitable to receive SBRT for the primary tumors after EGFR-TKI treatment. All selected patients were treated with first-line EGFR-TKIs and SBRT for their primary lesions. The primary endpoints were the progression-free survival 1 (PFS1, time of first TKI dose relative to disease progression based on RECIST) and PFS2 (time of first TKI dose relative to disease progression after SBRT). The secondary endpoints were overall survival (OS) and safety.
Results: Seventy-nine patients were enrolled, including 45 patients who received SBRT for their primary tumor at the maximal response of EGFR-TKI (the preemptive RT group) and 34 patients who received SBRT for their primary tumor after the occurrence of oligoprogression (the delayed RT group). The preemptive RT group had a significantly better median PFS1 than the delayed RT group (22.3 months vs. 12.9 months, P = 0.0031). The median PFS2 in the preemptive RT and delayed RT groups were 22.3 and 28.9 months, respectively (P = 0.17). The median OS did not differ significantly between the preemptive RT group and the delayed RT group (46.6 versus 51.3 months, P = 0.54). No severe toxicities (≥ grade 3) were recorded.
Conclusion: This real-world study showed that preemptive RT to primary lung tumors is a feasible option for selected patients with EGFR-mutant non-oligometastatic NSCLC who had stable disease during first-line EGFR-TKI treatment, and that it significantly improved PFS.