Efficacy and Toxicity of Robotic Stereotactic Body Radiotherapy of Lung Metastases in Patients With Oligometastatic Disease

Abstract

Background: Stereotactic body radiotherapy is a locally effective treatment for lung metastases in patients with oligometastatic disease, a modern variant of which is robotic (rSBRT). Since it is unclear which factors determine the success of rSBRT, we investigated a cohort of patients with lung metastases treated with rSBRT. Patients and Methods: In our retrospective single-center analysis, we included patients with oligometastatic disease of different cancer types who underwent SBRT of lung metastases using an Accuray Cyberknife^® device between 2012 and 2019. We evaluated local control rate (LC), progression-free (PFS) and overall (OS) survival, and toxicity. Multivariate analysis was performed to identify independent factors associated with the efficacy and toxicity of rSBRT. Results: A total of 70 lung metastases of 54 patients were evaluated. The 4-year Kaplan–Meier estimate for LC, PFS and OS were 72.0%, 12.4% and 49.7%, respectively. Cox regression showed that LC of metastases of colorectal carcinoma and metastases treated with a biological effective dose at an α/β-ratio of 10 (BED₁₀) of <100 Gy was significantly worse than for other metastases. Patients suffered from grade I-II pneumonitis in 21.4% of cases treated with rSBRT (grade I: 20.0%; grade II: 1.4%). Conclusion: rSBRT is an effective and safe therapy for lung metastases. A BED₁₀ of >100 Gy should be aimed for, especially for potentially radioresistant histologies such as colorectal carcinoma.