A Comparative Study of Patients With Early-Stage Non-Small Cell Lung Cancer Treated With Stereotactic Body Radiation Therapy Using CyberKnife and Linear Accelerator–Based Volumetric Modulated Arc Therapy

Purpose: Stereotactic body radiation therapy (SBRT) has become the standard of care for medically inoperable early-stage non-small cell lung cancer. We investigated 2 modalities of lung SBRT, CyberKnife (CK) and volumetric modulated arc therapy (VMAT), for differences in dosimetric parameters, tumor control, and clinical outcomes. Methods and Materials: Patients who underwent SBRT for T1-2N0M0 non-small cell lung cancer from 2012 to 2018 were included. Dosimetric parameters for target volume coverage and organ-at-risk dose distribution were collected. Survival outcomes were evaluated using the Kaplan-Meier method with log-rank test. A multivariate Cox proportional hazards model was analyzed for local, regional, and distant tumor control; overall survival (OS) and progression-free survival; and radiation pneumonitis. Results: Two hundred twenty-seven patients (142 CK, 85 VMAT SBRT) met inclusion criteria. Overall, the local, regional, and distant control rates were 89.3%, 86.3%, and 87.4% at 2 years, and the OS was 67.5% and 32.8% at 2 and 5 years, respectively. VMAT delivered higher maximum doses to the gross tumor volume and planning target volume and had a lower lung and heart V₅. Although there was no difference in local or distant failure, progression-free survival, or OS, VMAT was associated with superior freedom from regional failure (adjusted hazard ratio, 0.26; P = .045). With no difference between treatment modalities, 11.9% of patients developed grade 1 to 2 radiation pneumonitis. There were no grade 3+ events of radiation pneumonitis. Conclusions: This study revealed that VMAT and CK provided comparable local and distant control and survival outcomes; however, VMAT exhibited better regional control. Further study in this regard is imperative.