Hypofractionated Stereotactic Body Radiation Therapy With Simultaneous Integrated Boost With Flattening Filter-Free Volumetric Modulated Arc Therapy for Spinal Metastases

A novel approach could be the use of hypofractionated stereotactic body radiation therapy with simultaneous integrated boost (HSBRT-SIB) with flattening filter-free volumetric modulated arc therapy (FFF-VMAT) for spinal metastases. The aim of the present study is to report the clinical results of the treatment modality.The patients with spinal metastases (n ≤ 3) were treated in our institution with HSBRT-SIB using FFF-VMAT. The radiographically visible tumor was contoured as gross tumor volume (GTV). Clinical target volume (CTV) was defined according to international consensus guidelines. 25 Gy/5F to the planning target volume (PTV) and 35 Gy/5F to GTV were generated on the treatment planning system with FFF-VAMT. The primary endpoints were the tumor local control and pain control; the secondary ones were the overall survival and toxicity. Toxicity was assessed according to the Common Terminology Criteria for Adverse Events (CTCAE) v4.0.31 spinal metastases in 27 patients were treated with HSBRT-SIB from December 2017 to December 2019. There were 18 male and 9 female patients (median age, 59 years; range 24 to 79 years). The primary tumors were lung cancer (n = 13), hepatocellular carcinoma (n = 3), nasopharyngeal carcinoma (n = 2), colon cancer (n = 2), breast cancer (n = 1), prostate cancer (n = 1) and others (n = 5). 21 treatments included at least two vertebrae. 22 and 10 had paraspinal and epidural involvement, respectively. 7 had pathological fractures. With a median follow-up of 13 months (range 3-37 months), 1 lesion had a local failure, and 1 lesion had a relapse at 11 months. The local control rates at 1 year were 89.1%. The overall survival at 1 year were 55.6%. 85.1% of the patients had a complete pain remission and 14.9% had a partial pain remission. No adverse events ≥3 grade were observed.The use of HSBRT-SIB for spinal metastases is safe, and provides excellent local control and pain control.X. Liu: None. X. Li: None. P. Zhang: None. H. Yan: None. Y. Peng: None. N. Zou: None.