Simultaneous stereotactic radiosurgery of multiple brain metastases using single isocenter dynamic conformal arc therapy: a prospective monocentric registry trial

Background Single-isocenter dynamic conformal arc (SIDCA) therapy is an efficient way of delivering stereotactic radiosurgery (SRS) to multiple metastases simultaneously. This study reports on the safety and feasibility of SRS with SIDCA for patients with multiple brain metastases.Methods All patients who received SRS with this technique between November 2017 and June 2019 within a prospective registry trial, were included. The patients were irradiated using a VersaHD® linear accelerator (LINAC) from Elekta (Stockholm, Sweden). Follow-up was performed every three months, including a clinical and radiological examination with cranial magnetic resonance imaging (MRI). The data were analyzed using descriptive statistics and the Kaplan-Meier method.Results 65 patients with 254 lesions (range 2–12) were included in this analysis. Median beam on time was 23 minutes. The median follow-up at the time of analysis was 13 months (95% CI 11.1–14.9). Median overall survival and median progression-free survival was 15 months (95% CI 7.7–22.3) and 18 months (95% CI 11.1–24.9), respectively. Intracranial and local control after 6 months was 73.0% and 97.5%, respectively. During follow-up, CTCAE grade 1 adverse effects (AE) were experienced by 29 (44.6%) patients (18 of them therapy-related (27.7%)), CTCAE grade 2 AEs by 4 (6.2%) patients (one of them therapy-related (1.5%)) and CTCAE grade 3 by 3 patients (4.6%) (none of them therapy-related). 2 lesions (0.8%) in 2 patients (3.1%) were proven as radiation necrosis. Conclusions Simultaneous SRS using SIDCA seems to be a feasible and safe treatment for patients with multiple metastases.