Phase I clinical evaluation of near-simultaneous computed tomographic image-guided stereotactic body radiotherapy for spinal metastases.
OBJECTIVE
To evaluate in a Phase I study the safety, feasibility, and patient-positioning accuracy of treating patients with intensity-modulated, near-simultaneous, computed tomographic (CT) image-guided stereotactic body radiotherapy (SBRT).


METHODS
Fifteen consecutive patients with metastatic spinal disease who met protocol eligibility criteria were entered into a Phase I clinical trial. Each patient received five treatments of intensity-modulated, near-simultaneous CT image-guided SBRT, for a total of 75 treatments with 90 isocenter setups during the course of the study. Patients uniformly received 30 Gy (if possible) of radiotherapy in 5 fractions to the clinical target volume. The total dose was constrained by limiting the spinal cord to a maximum dose of 10 Gy. To verify correct daily patient positioning before each treatment and to determine the daily treatment setup error after radiation delivery, axial CT scans were taken before and immediately after each treatment without moving the patient from the treatment position, for comparison with the planning CT scan. Toxicity was measured using the Common Toxicity Criteria, the Late Effects of Normal Tissue scoring system and a neurologic function scale. Follow-up was conducted 4 weeks after completion of SBRT, and then 2, 3, 6, 9, 12, and every 6 months thereafter.


RESULTS
The procedure was technically feasible to perform in all patients. No neurologic toxicity was observed in any patient. The median follow-up time was 9 months (range 6-16). The Clopper-Pearson upper bound on the probability of paralysis with 95% confidence is no greater than 0.181. The positional setup error was determined to be within 1 mm of planning isocenter.


CONCLUSIONS
This Phase I study shows that intensity-modulated, near simultaneous, CT image-guided SBRT is a feasible, and highly precise technique for the noninvasive treatment of spinal metastases. Although no paralysis has developed in the 15 patients treated, continued monitoring for spinal cord toxicity is warranted, as larger numbers of patients will be needed to more precisely define the upper bound on the probability of spinal cord myelopathy.
Department of Radiation Oncology, Unit 97, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA. echang@mdanderson.org
Eric L
EL
Chang
Almon S
AS
Shiu
Ming-Fwu
MF
Lii
Laurence D
LD
Rhines
Ehud
E
Mendel
Anita
A
Mahajan
Jeffrey S
JS
Weinberg
Leni A
LA
Mathews
Barry W
BW
Brown
Moshe H
MH
Maor
James D
JD
Cox
D000293:Adolescent; D000328:Adult; D000368:Aged; D016001:Confidence Intervals; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods*; D013125:Spinal Neoplasms / Q000532:radiotherapy* / Q000556:secondary*; D013238:Stereotaxic Techniques / Q000009:adverse effects; D014057:Tomography, X-Ray Computed / Q000379:methods*