Treatment of early non-small cell lung cancer, stage IA, by image-guided robotic stereotactic radioablation--CyberKnife.

OBJECTIVE: To evaluate the efficacy of using image-guided robotic stereotactic radioablation as an alternative treatment modality for patients with surgically resectable, but medically inoperable, T1 N0 M0, stage IA non-small cell lung cancer.
METHODS: Between January 2004 and May 2006, 19 patients, 11 women and 8 men ranging in age from 52 to 88 years, with stage IA non-small cell lung cancer were treated. Tumor volume ranged from 1.7 to 13 mL. Total doses ranged from 24 to 60 Gy delivered in 3 fractions. Eleven patients received 60 Gy. Real-time target localization was accomplished by radiographic detection of fiducial marker(s) implanted within the tumor combined with respiratory motion tracking.
RESULTS: All patients tolerated radioablation well with fatigue as the main side effect. Fourteen patients are alive from 1 to 25 months posttreatment. Four patients died: 2 of comorbid disease and 2 of cancer progression (status post 60 and 55.5 Gy). Three patients developed grade I radiation pneumonitis. Two patients have stable disease. In 3 patients, cancer recurred in the planning treatment volume: in 2 patients after treatment with 60 Gy and in 1 patient after treatment with 55.5 Gy. One patient had local control in the target volume but developed metastasis to the ipsilateral hilum. Nine patients had a complete response and show no evidence of disease.
CONCLUSIONS: In our early experience, stereotactic radioablation using the CyberKnife system appears to be a safe, minimally invasive, and effective modality for treating early stage lung cancer in patients with medically inoperable disease. Dose escalation and/or increasing the treatment volumes, with the aid of the high conformality of this technique, may help to achieve further improvements in these promising results.