Lung optimized treatment with cyberknife® in inoperable lung cancer patients: Feasibility analysis of a mono-institutional 115 patient series

CyberKnife® Lung Optimized Treatment (LOT) allows the treatment of lung cancer without invasive fiducial implanta-tion. The aim of this retrospective analysis was to evaluate the feasibility, toxicity and clinical outcome. One hundred fifteen patients (124 lesions) were treated with CyberKnife® using LOT. The median age was 72.6 years (range 31.8–90.3). From 124 treated lesions, 52 were with histopathological confirmation (41 primitive pulmonary cancers, 8 pulmonary metastases) and 72 as untyped tumors. For 5 patients (6 lesions) treatment was an in-field re-irradiation. Concomitant therapy was administered in 7 patients. Zero-View tracking was applied in 69 patients, 1-View in 33 patients, 2-View in 22 patients. The median total dose was 45 Gy (range 18–54), median dose/fraction was 15 Gy (range 4–18) with a median prescription isodose of 80% (range 68–85). The median planning target volume (PTV) was 25 cm3 (range 3–195). The median follow-up was 20 months (range 7–47). Thirty-seven patients (32%) were alive with no evidence of disease, 39 patients (34%) were alive with clinically evident disease, and 38 patients (33%) died of the disease. The 1-and 2-year overall survival (OS) rate was 83% and 61%. The median time to progression was 19 months (95% confidence interval: 11–19 months), 1-and 2-year progression-free survival (PFS) rates were 62% and 41%, respectively. Smaller PTV was significantly associated with better OS, PFS and in-field PFS in univariate and multivariate analyses. Acute toxicity was observed in 36 patients (41%). Late toxicity was registered in 25 patients (29%). G3 late toxicity was observed in one patient (1.1%). Our data suggest that fiducial less-stereotactic body radiation therapy (SBRT) is a feasible, well-tolerated and potentially effective treatment with high compliance in the setting of inoperable patients due to concomitant disease or previous treatments.