Hypofractionated image-guided breath-hold SABR (Stereotactic Ablative Body Radiotherapy) of liver metastases – clinical results

摘要

Purpose Stereotactic Ablative Body Radiotherapy (SABR) is a non-invasive therapy option for inoperable liver oligometastases. Outcome and toxicity were retrospectively evaluated in a single-institution patient cohort who had undergone ultrasound-guided breath-hold SABR. Patients and methods 19 patients with liver metastases of various primary tumors consecutively treated with SABR (image-guidance with stereotactic ultrasound in combination with computer-controlled breath-hold) were analysed regarding overall-survival (OS), progression-free-survival (PFS), progression pattern, local control (LC), acute and late toxicity. Results PTV (planning target volume)-size was 108?±?109cm3 (median 67.4?cm3). BED2 (Biologically effective dose in 2?Gy fraction) was 83.3?±?26.2?Gy (median 78?Gy). Median follow-up and median OS were 12?months. Actuarial 2-year-OS-rate was 31%. Median PFS was 4?months, actuarial 1-year-PFS-rate was 20%. Site of first progression was predominantly distant. Regression of irradiated lesions was observed in 84% (median time to detection of regression was 2?months). Actuarial 6-month-LC-rate was 92%, 1- and 2-years-LC-rate 57%, respectively. BED2 influenced LC. When a cut-off of BED2?=?78?Gy was used, the higher BED2 values resulted in improved local control with a statistical trend to significance (p?=?0.0999). Larger PTV-sizes, inversely correlated with applied dose, resulted in lower local control, also with a trend to significance (p-value?=?0.08) when a volume cut-off of 67?cm3 was used. No local relapse was observed at PTV-sizes?3 and BED2?>?78?Gy. No acute clinical toxicity?>?°2 was observed. Late toxicity was also?≤?°2 with the exception of one gastrointestinal bleeding-episode 1?year post-SABR. A statistically significant elevation in the acute phase was observed for alkaline-phosphatase; in the chronic phase for alkaline-phosphatase, bilirubine, cholinesterase and C-reactive protein. Conclusions A trend to statistically significant correlation of local progression was observed for BED2 and PTV-size. Dose-levels BED2?>?78?Gy cannot be reached in large lesions constituting a significant fraction of this series. Image-guided SABR (igSABR) is therefore an effective non-invasive treatment modality with low toxicity in patients with small inoperable liver metastases.