Stereotactic body radiotherapy for lesions of the spine and paraspinal regions.
OBJECTIVE
To describe our experience and clinical strategy for stereotactic body radiotherapy (SBRT) of spinal lesions.


METHODS
Thirty-two patients with 33 spinal lesions underwent computed tomography-based simulation while free breathing. Gross/clinical target volumes included involved portions of the vertebral body and paravertebral/epidural tumor. Planning target volume (PTV) expansion was 6 mm axially and 3 mm radially; the cord was excluded from the PTV. Biologic equivalent dose was calculated using the linear quadratic model with alpha/beta = 3 Gy. Treatment was linear accelerator based with on-board imaging; dose was adjusted to maintain cord dose within tolerance. Survival, local control, pain, and neurologic status were monitored.


RESULTS
Twenty-one patients are alive at 1 year (median survival, 14 months). Median follow-up is 6 months for all patients (7 months for survivors). Mean previous radiotherapy dose to 22 patients was 35 Gy, and median interval was 17 months. Renal (31%), breast, and lung (19% each) were the most common histologic sites. Three SBRT fractions (range, one to four fractions) of 7 Gy (range, 5-16 Gy) were delivered. Median cord and target biologic equivalent doses were 70 Gy(3) and 34.3 Gy(10), respectively. Thirteen patients reported complete and 17 patients reported partial pain relief at 1 month. There were four failures (mean, 5.8 months) with magnetic resonance imaging evidence of in-field progression. No dosimetric parameters predictive of failure were identified. No treatment-related toxicity was seen.


CONCLUSIONS
Spinal SBRT is effective in the palliative/re-treatment setting. Volume expansion must ensure optimal PTV coverage while avoiding spinal cord toxicity. The long-term safety of spinal SBRT and the applicability of the linear-quadratic model in this setting remain to be determined, particularly the time-adjusted impact of prior radiotherapy.
Nelson
John W
JW
Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA.
Yoo
David S
DS
Sampson
John H
JH
Isaacs
Robert E
RE
Larrier
Nicole A
NA
Marks
Lawrence B
LB
Yin
Fang-Fang
FF
Wu
Q Jackie
QJ
Wang
Zhiheng
Z
Kirkpatrick
John P
JP
D000368:Aged; D000369:Aged, 80 and over; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D020714:Maximum Tolerated Dose; D008875:Middle Aged; D059408:Pain Management; D010166:Palliative Care / Q000379:methods; D011832:Radiation Injuries / Q000517:prevention & control; D011836:Radiation Tolerance; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D012062:Relative Biological Effectiveness; D013116:Spinal Cord / Q000528:radiation effects; D013125:Spinal Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000556:secondary / Q000601:surgery*; D047368:Tumor Burden