The outcome of CyberKnife treatment for primary or metastatic malignant lung tumors

Background: To analyze the local control of malignant lung tumors and survival of nonsmall cell lung cancer (NSCLC) patients after stereotactic ablative radiotherapy with CyberKnife. Materials and Methods: Patients with malignant lung tumors treated by CyberKnife between July 2007 and October 2010 at our institute were retrospectively reviewed. A total of 55 patients with 110 malignant lung tumors were included. There were 32 men and 23 women, and the median age was 67 years. There were 11 early-stage NSCLCs, while the other 44 patients with 99 lesions were metastatic lung tumors. The median gross tumor volume was 13.3 ml. Radiotherapy schedules include 40-60 Gy in 4-5 fractions, 45-60 Gy in 3 fractions and 30 Gy in 1 fraction. Results: The median follow-up time for patients alive was 34 months. The local control rates for all tumors were 96% at 1-year and 80% at 2 years. Univariate analysis demonstrated that target volume was important for local control. Biologically equivalent dose (BED) ≥100 Gy provided significantly higher chance to achieve a complete response than BED <100 Gy. The disease-specific survival rates for early-stage NSCLC were 80% at 1-year and 60% at 2 years. Treatment related complications were acceptable. No grade 2-5 adverse events were noted. Conclusions: CyberKnife can be used for NSCLC and metastatic lung tumors, either peripheral or central location, with good local control and acceptable side-effects.