Outcomes for Spine Stereotactic Body Radiation Therapy and an Analysis of Predictors of Local Recurrence

Journal Article · Sat Aug 01 04:00:00 EDT 2015 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/J.IJROBP.2015.03.037· OSTI ID:22462397

Bishop, Andrew J.; Tao, Randa ^[1]; Rebueno, Neal C. ^[2]; Christensen, Eva N.; Allen, Pamela K. ^[1]; Wang, Xin A. ^[3]; Amini, Behrang ^[4]; Tannir, Nizar M. ^[5]; Tatsui, Claudio E.; Rhines, Laurence D. ^[6]; Li, Jing ^[1]; Chang, Eric L. ^[7]; Brown, Paul D. ^[1]

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1. Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
2. Department of Radiation Dosimetry, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
3. Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
4. Department of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
5. Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
6. Department of Neurosurgery, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
7. Department of Radiation Oncology, USC Norris Cancer Hospital, Keck School of Medicine of USC, Los Angeles, California (United States)

Purpose: To investigate local control, survival outcomes, and predictors of local relapse for patients treated with spine stereotactic body radiation therapy. Methods and Materials: We reviewed the records of 332 spinal metastases consecutively treated with stereotactic body radiation therapy between 2002 and 2012. The median follow-up for all living patients was 33 months (range, 0-111 months). Endpoints were overall survival and local control (LC); recurrences were classified as either in-field or marginal. Results: The 1-year actuarial LC and overall survival rates were 88% and 64%, respectively. Patients with local relapses had poorer dosimetric coverage of the gross tumor volume (GTV) compared with patients without recurrence (minimum dose [Dmin] biologically equivalent dose [BED] 23.9 vs 35.1 Gy, P<.001; D98 BED 41.8 vs 48.1 Gy, P=.001; D95 BED 47.2 vs 50.5 Gy, P=.004). Furthermore, patients with marginal recurrences had poorer prescription coverage of the GTV (86% vs 93%, P=.01) compared with those with in-field recurrences, potentially because of more upfront spinal canal disease (78% vs 24%, P=.001). Using a Cox regression univariate analysis, patients with a GTV BED Dmin ≥33.4 Gy (median dose) (equivalent to 14 Gy in 1 fraction) had a significantly higher 1-year LC rate (94% vs 80%, P=.001) compared with patients with a lower GTV BED Dmin; this factor was the only significant variable on multivariate Cox analysis associated with LC (P=.001, hazard ratio 0.29, 95% confidence interval 0.14-0.60) and also was the only variable significant in a separate competing risk multivariate model (P=.001, hazard ratio 0.30, 95% confidence interval 0.15-0.62). Conclusions: Stereotactic body radiation therapy offers durable control for spinal metastases, but there is a subset of patients that recur locally. Patients with local relapse had significantly poorer tumor coverage, which was likely attributable to treatment planning directives that prioritized the spinal cord constraints over tumor coverage. When possible, we recommend maintaining a GTV Dmin above 14 Gy in 1 fraction and 21 Gy in 3 fractions.

• OSTI ID: 22462397
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 5 Vol. 92; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
COMPARATIVE EVALUATIONS
DOSE EQUIVALENTS
HAZARDS
LIMITING VALUES
METASTASES
MULTIVARIATE ANALYSIS
NEOPLASMS
PATIENTS
PLANNING
RADIATION DOSES
RADIOTHERAPY
REVIEWS
SPINAL CORD
VERTEBRAE