Clinical outcomes of 130 patients with primary and secondary lung tumors treated with Cyberknife robotic stereotactic body radiotherapy

Background: Authors report clinical outcomes of patients treated with robotic stereotactic body radiotherapy (SBRT) for primary, recurrent and metastatic lung lesions. Materials and methods: 130 patients with  160 lesions were treated with Cyberknife SBRT,including T1-3 primary lung cancers (54 %), recurrent tumors (22%) and pulmonary metastases (24%). The mean biologically equivalent dose (BED 10Gy) was 151 Gy (72-180 Gy). Median prescribed dose for peripheral and central lesions was 3x20 Gy and 3x15 Gy, respectively. Local control (LC), overall survival (OS), and cause-specific survival (CSS) rates, early and late toxicities are reported. Statistical analysis was performed to identify factors influencing local tumor control. Results: Median follow-up time was 21 months. In univariate analysis, higher dose was associated with better LC and a cut-off value was detected at BED 10Gy ≤112.5 Gy, resulting in 1-, 2-, and 3-year actuarial LC rates of 93%, vs 73%, 80% vs 61%, and 63% vs 54%, for the high and low dose groups, respectively (p=0.0061, HR=0.384). In multivariate analysis, metastatic origin, histological confirmation and larger Planning Target Volume (PTV) were associated with higher risk of local failure. Actuarial OS and CSS rates at 1, 2, and 3 years were 85%, 74% and 62%, and 93%, 89% and 80 %, respectively. Acute and late toxicities ≥ Gr 3 were observed in 3 (2%) and 6 patients (5%), respectively. Conclusion: Our favorable LC and survival rates after robotic SBRT are coherent with the literature in this mixed, non-selected study population, with low rates of severe toxicities.