Purpose: The aims of this study were to determine if image-guided robotic stereotactic radiosurgery by CyberKnife Radiosurgery System using ablative radiation doses achieves acceptable local control in medically inoperable patients with early non-small-cell lung cancer (NSCLC) and to evaluate disease-free survival, toxicity, and failure. CyberKnife can deliver the prescribed dose by using many different angles converging on the target, with real-time target tracking through a combined orthogonal radiograph imaging and optic motion tracking system (Synchrony).
Materials and methods: A review of treatment details and outcomes for 59 patients, ranging in age from 51 years to 96 years, with 61 tumors with histologically proven cancers treated by image-guided robotic stereotactic radiosurgery at the CyberKnife Center of Miami between March 2004 and March 2007 is presented. Target localization and respiratory movement compensation were accomplished using a single fiducial marker placed within the tumor, and the X-Sight and Synchrony systems. Total doses ranged from 15 Gy to 67.5 Gy delivered in 1-5 fractions with an equivalent dose range of 24-110 Gy normalized treatment dose in 2 Gy fractions (alpha/beta = 20 Gy).
Results: Four patients with stage 1A NSCLC and 2 patients with stage 1B NSCLC had persistent or recurrent disease. All patients tolerated the radiosurgery well, fatigue being the main side effect. Of the 59 patients treated, 51 (86%) were still alive at 1-33-month follow-up. Eight patients have died, 2 of diseases other than cancer progression.
Conclusion: The results indicate that the delivery of precisely targeted ablative radiation doses with surgical precision to limited treatment volumes of lung tumors in a hypofractionated fashion is feasible and safe. Image-guided robotic stereotactic radiosurgery of lung tumors with CyberKnife(R) achieves excellent rates of local disease control with limited toxicity to surrounding tissues and, in many cases, might be curative for patients for whom surgery is not an option.