title: Stereotactic body radiotherapy for metastatic spinal sarcoma: a detailed patterns-of-failure study.
abstract: OBJECTIVE The aim of this study was to report the first detailed analysis of patterns of failure within the spinal axis of patients treated with stereotactic body radiotherapy (SBRT) for sarcoma spine metastases. METHODS Between 2005 and 2012, 88 consecutive patients with metastatic sarcoma were treated with SBRT for 120 spinal lesions. Seventy-one percent of patients were enrolled on prospective institutional protocols. For patients who underwent routine posttreatment total-spine MRI (64 patients, 88 lesions), each site of progression within the entire spinal axis was mapped in relation to the treated lesion. Actuarial rates of local-, adjacent-, and distant-segment failure-free survival (FFS) were calculated using the Kaplan-Meier method. RESULTS The median follow-up for the cohort was 14.4 months, with 81.7% of patients followed up until death. The 12-month actuarial rate of local FFS was 85.9%; however, 83.3% of local failures occurred in conjunction with distant-segment failures. The 12-month actuarial rates of isolated local-, adjacent-, and distant-segment FFS were 98.0%, 97.8%, and 74.7%, respectively. Of patients with any spinal progression (n = 55), only 25.5% (n = 14) had progression at a single vertebral level, with 60.0% (n = 33) having progression at ≥ 3 sites within the spine simultaneously. Linear regression analysis revealed a relationship of decreasing risk of failure with increasing distance from the treated index lesion (R(2) = 0.87), and 54.1% of failures occurred ≥ 5 vertebral levels away. Treatment of the index lesion with a lower biological effective dose (OR 3.2, 95% CI 1.1-9.2) and presence of local failure (OR 18.0, 95% CI 2.1-152.9) independently predicted for distant spine failure. CONCLUSIONS Isolated local- and adjacent-segment failures are exceptionally rare for patients with metastatic sarcoma to the spine treated with SBRT, thereby affirming the treatment of the involved level only. The majority of progression within the spinal axis occurs ≥ 5 vertebral levels away. Thus, total-spine imaging is necessary for surveillance posttreatment.
authors.affiliation: Departments of 1 Radiation Oncology and.
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Leeman
authors.affiliation: Departments of 1 Radiation Oncology and.
authors.forename: Mark
authors.initials: M
authors.lastname: Bilsky
authors.affiliation: Departments of 1 Radiation Oncology and.
authors.forename: Ilya
authors.initials: I
authors.lastname: Laufer
authors.affiliation: Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas and.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Folkert
authors.affiliation: Departments of 1 Radiation Oncology and.
authors.forename: Neil K
authors.initials: NK
authors.lastname: Taunk
authors.affiliation: Radiology, Memorial Sloan Kettering Cancer Center, New York, New York;
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Osborne
authors.affiliation: Radiology, Memorial Sloan Kettering Cancer Center, New York, New York;
authors.forename: Julio
authors.initials: J
authors.lastname: Arevalo-Perez
authors.affiliation: Departments of 1 Radiation Oncology and.
authors.forename: Joan
authors.initials: J
authors.lastname: Zatcky
authors.affiliation: Departments of 1 Radiation Oncology and.
authors.forename: Kaled M
authors.initials: KM
authors.lastname: Alektiar
authors.affiliation: Departments of 1 Radiation Oncology and.
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Yamada
authors.affiliation: Departments of 1 Radiation Oncology and.|Department of Radiation Oncology, University of Michigan Medical Center, Ann Arbor, Michigan.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Spratt
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D012509:Sarcoma / Q000000981:diagnostic imaging / Q000601:surgery*; D013125:Spinal Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary / Q000601:surgery*; D016896:Treatment Outcome
keywords: AFFS = adjacent-segment failure-free survival; DFFS = distant-segment failure-free survival; FA = flip angle; LFFS = local failure-free survival; OS = overall survival; SBRT; SBRT = stereotactic body radiotherapy; oncology; patterns of failure; sarcoma; spine metastasis; stereotactic body radiotherapy