Outcome of four-dimensional stereotactic radiotherapy for centrally located lung tumors

Purpose: To assess local control, overall survival, and toxicity of four-dimensional, risk-adapted stereotactic body radiotherapy (SBRT) delivered while tracking respiratory motion in patients with primary and metastatic lung cancer located in the central chest. Methods: Fifty-eight central lesions of 56 patients (39 with primary, 17 with metastatic tumors) were treated. Fifteen tumors located near the esophagus were treated with 6 fractions of 8 Gy. Other tumors were treated according to the following dose escalation scheme: 5 fractions of 9 Gy (n = 6), then 5 fractions of 10 Gy (n = 15), and finally 5 fractions of 12 Gy (n = 22). Results: Dose constraints for critical structures were generally achieved; in 21 patients the coverage of the PTV was reduced below 95% to protect adjacent organs at risk. At a median follow-up of 23 months, the actuarial 2-years local tumor control was 85% for tumors treated with a BED > 100 Gy compared to 60% for tumors treated with a BED <= 100 Gy. No grade 4 or 5 toxicity was observed. Acute grade 1-2 esophagitis was observed in 11% of patients. Conclusion: SBRT of central lung lesions can be safely delivered, with promising early tumor control in patients many of whom have severe comorbid conditions. (c) 2012 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 102 (2012) 383-387