title: Single-fraction versus multifraction spinal stereotactic radiosurgery for spinal metastases from renal cell carcinoma: secondary analysis of Phase I/II trials.
abstract: OBJECTIVE 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. METHODS 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. RESULTS 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) CONCLUSIONS 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.
authors.affiliation: Departments of 1 Radiation Oncology.
authors.forename: Amol J
authors.initials: AJ
authors.lastname: Ghia
authors.affiliation: Department of Radiation Oncology, USC Norris Cancer Center, Los Angeles, California.
authors.forename: Eric L
authors.initials: EL
authors.lastname: Chang
authors.affiliation: Departments of 1 Radiation Oncology.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Bishop
authors.affiliation: Departments of 1 Radiation Oncology.
authors.forename: Hubert Y
authors.initials: HY
authors.lastname: Pan
authors.affiliation: Departments of 1 Radiation Oncology.
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Boehling
authors.affiliation: Radiology, University of Texas MD Anderson Cancer Center, Houston, Texas; and.
authors.forename: Behrang
authors.initials: B
authors.lastname: Amini
authors.affiliation: Departments of 1 Radiation Oncology.
authors.forename: Pamela K
authors.initials: PK
authors.lastname: Allen
authors.affiliation: Departments of 1 Radiation Oncology.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: Neurosurgery, and.
authors.forename: Laurence D
authors.initials: LD
authors.lastname: Rhines
authors.affiliation: Medical Oncology.
authors.forename: Nizar M
authors.initials: NM
authors.lastname: Tannir
authors.affiliation: Neurosurgery, and.
authors.forename: Claudio E
authors.initials: CE
authors.lastname: Tatsui
authors.affiliation: Departments of 1 Radiation Oncology.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Brown
authors.affiliation: Departments of 1 Radiation Oncology.
authors.forename: James N
authors.initials: JN
authors.lastname: Yang
mesh_terms: D000328:Adult; D000368:Aged; D002292:Carcinoma, Renal Cell / Q000556:secondary / Q000601:surgery*; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D013125:Spinal Neoplasms / Q000556:secondary / Q000601:surgery*; D013238:Stereotaxic Techniques
keywords: BED = biological equivalent dose; Dmax = maximum point dose; Dmin = minimum point dose; GTV = gross tumor volume; HR = hazard ratio; IMRT = intensity-modulated radiotherapy; KPS = Karnofsky Performance Scale; LC = local control; MF = multifraction; RCC = renal cell carcinoma; SF = single fraction; SHR = subhazard ratio; SINS = Spine Instability Neoplastic Score; SSRS = spinal stereotactic radiosurgery; fraction; metastases; nBED = normalized BED; oncology; radiation; stereotactic body radiotherapy