2505 - Comparison of Changes in Pulmonary Function after SBRT vs. Surgery for Early-Stage Non-Small Cell Lung Cancer: A Prospective Real-World Observational Study

Purpose/Objective(s): This study aims to investigate whether SBRT treatment protects pulmonary function in early-stage non-small cell lung cancer (ES-NSCLC) patients across different follow-up time points. Furthermore, we explore the association between changes in pulmonary function and alterations in lung volume after SBRT.

Materials/Methods: This single-center prospective study included ES-NSCLC patients with interlobar pleural involvement confirmed by imaging. Pulmonary function tests and CT imaging data were obtained at baseline (prior to treatment), two months after treatment completion, and every three months thereafter for a follow-up period of two years. The primary endpoint of our study was to compare the changes in FEV1, MMEF25/75 and DLCO from baseline at each follow-up time point between the SBRT group and the surgery group. The secondary endpoint of our study was to evaluate the relationship between changes in the volume of ROI (including consolidation regions and GGO regions) and changes in pulmonary function.

Results: As of the January 2025 interim analysis, 119 participants were prospectively evaluated, with 86 in the surgical resection cohort and 33 in the stereotactic body radiotherapy (SBRT) cohort. Longitudinal pulmonary function trajectories revealed distinct patterns between the two treatment groups: Surgery group exhibited consistent reductions in FEV1, showing dramatic declines compared to the SBRT group at all postoperative follow-up points (p-values: 3.4×10?6, 0.032, 0.006, 0.045, and 0.043 at 2, 5, 8, 11, and 14 months, respectively). Similar with FEV1, the decline of MMEF25/75 was more significant in surgery group at 2-, 5-, 8-, and 11-months postoperative follow-up points (p-values: 7.4×10?6, 3.4×10?6, 0.014, 0.002, respectively). Additionally, a statistically significant reduction in DLCO was observed in the surgical group at the 2-month postoperative follow-up (p=0.004), while no significant differences were noted at subsequent time points (p=0.990, p=0.850, p=0.130, p=0.490). Furthermore, the increase in the volume of consolidation regions demonstrated strong correlation with both pulmonary ventilation and diffusion capacity, with correlation coefficients of R=-0.81 (p<0.001) and R=-0.87 (p<0.001), respectively.

Conclusion: This study demonstrates that the SBRT group shows better FEV1 and MMEF25/75 preservation at each follow-up time point. Furthermore, it reveals that changes in the volume of consolidation regions are synchronized with changes in pulmonary function, exhibiting a strong correlation.