Postoperative Stereotactic Body Radiotherapy for Spinal Metastases and the Impact of Epidural Disease Grade

Abstract

BACKGROUND: Postoperative stereotactic body radiotherapy (pSBRT) is an emerging indication for spinal metastases (SM). OBJECTIVE: To report our experience with pSBRT for SM. METHODS: A retrospective chart review was performed for prospectively collected data of patients treated between September 2008 to December 2015 with pSBRT and followed with serial spinal MRIs every 2 to 3 mo until death or last follow-up. Univariate and multivariable analyses were performed to identify predictive factors. RESULTS: A total of 83 spinal segments in 47 patients treated with a median dose of 24 Gy in 2 fractions were included, with mostly lung and breast primaries. A total of 59.3% had preoperative high-grade epidural disease (ED) and 39.7% were unstable. The 12-mo cumulative incidence of local failure was 17% for all segments, and 33.3%, 21.8%, and 0% in segments with postoperative high-grade, low-grade, and no ED, respectively. Downgrading preoperative ED was predictive of better local control (P =. 03). The grade of postoperative ED was also predictive for local control (P