Single-fraction versus multifraction spinal stereotactic radiosurgery for spinal metastases from renal cell carcinoma: secondary analysis of Phase I/II trials

Abstract

<jats:sec> <jats:title>OBJECTIVE</jats:title> <jats:p>The objective of this study was to compare fractionation schemes and outcomes of patients with renal cell carcinoma (RCC) treated in institutional prospective spinal stereotactic radiosurgery (SSRS) trials who did not previously undergo radiation treatment at the site of the SSRS.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>Patients enrolled in 2 separate institutional prospective protocols and treated with SSRS between 2002 and 2011 were included. A secondary analysis was performed on patients with previously nonirradiated RCC spinal metastases treated with either single-fraction (SF) or multifraction (MF) SSRS.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>SSRS was performed in 47 spinal sites on 43 patients. The median age of the patients was 62 years (range 38–75 years). The most common histological subtype was clear cell (n = 30). Fifteen sites underwent surgery prior to the SSRS, with laminectomy the most common procedure performed (n = 10). All SF SSRS was delivered to a dose of 24 Gy (n = 21) while MF regiments were either 27 Gy in 3 fractions (n = 20) or 30 Gy in 5 fractions (n = 6). The median overall survival duration for the entire cohort was 22.8 months. The median local control (LC) for the entire cohort was 80.6 months with 1-year and 2-year actuarial LC rates of 82% and 68%, respectively. Single-fraction SSRS correlated with improved 1- and 2-year actuarial LC relative to MF SSRS (95% vs 71% and 86% vs 55%, respectively; p = 0.009). On competing risk analysis, SF SSRS showed superior LC to MF SSRS (subhazard ratio [SHR] 6.57, p = 0.014). On multivariate analysis for LC with tumor volume (p = 0.272), number of treated levels (p = 0.819), gross tumor volume (GTV) coverage (p = 0.225), and GTV minimum point dose (p = 0.97) as covariates, MF SSRS remained inferior to SF SSRS (SHR 5.26, p = 0.033)</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>SSRS offers durable LC for spinal metastases from RCC. Single-fraction SSRS is associated with improved LC over MF SSRS for previously nonirradiated RCC spinal metastases.</jats:p></jats:sec>

Non-Surgical Ablative Treatment of Distant Extracranial Metastases for Renal Cell Carcinoma: A Systematic Review

“…Interestingly, the Kaplan Meier curves for time to relapse were overlapping for the low single dose and hypofractionated cohorts, whereas the relapse curve for the high single dose was clearly superior. Ghia et al found a 1-year LCR of 95% after single dose 24Gy, versus 71% after a hypofractionated SBRT regimen (mostly 3x9Gy) [28]. In this study, single dose SBRT was the only significant predictor for superior local control on multivariate analysis.…”

“…We identified no studies on RFA that met the eligibility criteria. Eight studies on SBRT were included in the final review [23,[27][28][29][30][31][32][33]. Results are summarized in Table 1.…”

“…Six considered only bone metastases, mostly spine, two included mixed locations [27,32]. One study was prospective [28]. All studies included RCC only.…”

“…However, none of these had curative treatment of all metastases as main goal and none reported on metastatic load outside the treated location. Three studies did not find a significant difference in overall survival [28,30,32]. Two reported higher overall survival for SBRT compared with no or conventional radiotherapy respectively [27,33].…”

“…Due to different dosing regimens, the risk is difficult to estimate. One study reported however an incidence of 21% in 108 patients treated with single dose 16Gy [33], another an incidence of 46% in 13 patients treated with single dose 24Gy [28] and a third 5% in patients treated with single dose 18-24Gy [23]. In different hypofractionated SBRT regimens, the weighed incidence was 13% [23,28,30].…”