Clinical outcomes of single-fraction stereotactic radiation therapy of lung tumors

BACKGROUND. The objective of the current study was to investigate the effects and the morbidities of single-fraction stereotactic radiation therapy (SRT) for lung tumors. METHODS. A Microtron device was modified to deliver stereotactic irradiation under respiratory gating. Between August 1998 and December 2004, 59 malignant lung tumors (11 primary tumors, 48 metastases) that measured < 40 mm in greatest dimension were treated by single-fraction SRT. Nine tumors received a minimal dose of < 30 grays (Gy), and 50 tumors received a minimal dose of >= 30 Gy. The macroscopic target volume ranged from 1 cc to 19 cc (mean, 5 cc). RESULTS. The 1-year and 2-year local progression-free rates (LPFRs) were 93% and 78%, respectively. The overall survival rate was 76.5% at 1 year and 41% at 2 years. Local regrowth of the irradiated tumor was a direct cause of death in two patients. Only the minimal radiation dose to the reference target volume tended to have an influence on the LPFR (P = 0.068). The 2-year LPFRs for patients who received irradiation doses of >= 30 Gy and < 30 Gy were 83% and 52%, respectively. With regard to morbidities, Grade 3 respiratory symptoms (according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer late radiation morbidity scoring scheme) were noted in one patient. CONCLUSIONS. The results from the current study suggested that single-fraction SRT was tolerable and was capable of attaining excellent local control in patients who had malignant lung tumors that measured < 4 cm in greatest dimension.