Stereotactic body radiotherapy for lesions of the spine and paraspinal regions

Int J Radiat Oncol Biol Phys. 2009 Apr 1;73(5):1369-75. doi: 10.1016/j.ijrobp.2008.06.1949. Epub 2008 Nov 10.

Abstract

Purpose: To describe our experience and clinical strategy for stereotactic body radiotherapy (SBRT) of spinal lesions.

Methods and materials: 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.

Publication types

  • Evaluation Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Cone-Beam Computed Tomography
  • Female
  • Humans
  • Linear Models
  • Magnetic Resonance Imaging / methods
  • Male
  • Maximum Tolerated Dose
  • Middle Aged
  • Pain Management
  • Palliative Care / methods
  • Radiation Injuries / prevention & control
  • Radiation Tolerance
  • Radiosurgery / methods*
  • Radiotherapy Dosage
  • Radiotherapy Planning, Computer-Assisted / methods
  • Relative Biological Effectiveness
  • Spinal Cord / radiation effects
  • Spinal Neoplasms / diagnostic imaging
  • Spinal Neoplasms / mortality
  • Spinal Neoplasms / secondary
  • Spinal Neoplasms / surgery*
  • Tumor Burden