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.
Patients 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
(BED10Gy) 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 BED10Gy ≤ 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.
Conclusions: Our favorable LC and survival rates after robotic SBRT, with low rates of severe toxicities, are coherent
with the literature data in this mixed, non-selected study population.