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 α/β 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.
* Image-guided stereotactic radiosurgery provides an option for patients with resectable but medically inoperable metastatic lung tumors.
* In patients with limited pulmonary metastases, potent doses of image-guided robotic stereotactic radiosurgical system (IGR-SRS) are well tolerated with limited early toxicity.
* Local control rates are better than those obtained with conventional radiotherapy.
* Systematic research is necessary to clearly establish optimal treatment parameters.
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