Objectives: Based on the reported success of stereotactic body radiotherapy in treating extracranial tumors, we used CyberKnife (Accuray Incorporated, Sunnyvale, CA) to treat patients with metastatic lung cancer.
Methods: This is a retrospective report of treatment details and outcomes of 35 patients, ranging in age from 33 to 91 years, with 69 histologically proven pulmonary metastases, treated by image-guided robotic stereotactic radiosurgery at the CyberKnife Center of Miami, between March 2004 and August 2007. Tumor volumes ranged from 0.7 mL to 152 mL. Total doses ranged from 5 to 60 Gy delivered in one to four fractions with an equivalent dose range from 6 to 110 Gy NTD delivered in 2-Gy fractions assuming an alpha/beta of 20 Gy.
Results: All patients tolerated radiosurgery well with fatigue as the main side effect. Grade 3 and grade 4 pulmonary toxic reactions were observed in one patient who had undergone a repeat treatment. Of the 35 treated patients, 27 (77%) were still alive at a median 18-month (range 2-41 mo) follow-up. Local control was 71% with 25 tumors showing a complete response, 16 a partial response, and 7 stable with disease. Eight had progressive disease.
Conclusions: The delivery of precisely targeted radiation doses to lung tumors in a hypofractionated fashion is feasible and safe. Image-guided robotic stereotactic radiosurgery of pulmonary metastases with the CyberKnife achieves good rates of local disease control with limited toxicity to surrounding tissues and in many cases may be beneficial for patients for whom surgery is not an option.