Phase I/II study of stereotactic body radiotherapy for spinal metastasis and its pattern of failure.
OBJECTIVE
The authors report data concerning the safety, effectiveness, and patterns of failure obtained in a Phase I/II study of stereotactic body radiotherapy (SBRT) for spinal metastatic tumors.


METHODS
Sixty-three cancer patients underwent near-simultaneous computed tomography-guided SBRT. Spinal magnetic resonance imaging was conducted at baseline and at each follow-up visit. The National Cancer Institute Common Toxicity Criteria 2.0 assessments were used to evaluate toxicity.


RESULTS
The median tumor volume of 74 spinal metastatic lesions was 37.4 cm3 (range 1.6-358 cm3). No neuropathy or myelopathy was observed during a median follow-up period of 21.3 months (range 0.9-49.6 months). The actuarial 1-year tumor progression-free incidence was 84% for all tumors. Pattern-of-failure analysis showed two primary mechanisms of failure: 1) recurrence in the bone adjacent to the site of previous treatment, and 2) recurrence in the epidural space adjacent to the spinal cord. Grade 3 or 4 toxicities were limited to acute Grade 3 nausea, vomiting, and diarrhea (one case); Grade 3 dysphagia and trismus (one case); and Grade 3 noncardiac chest pain (one case). There was no subacute or late Grade 3 or 4 toxicity.


CONCLUSIONS
Analysis of the data obtained in the present study supports the safety and effectiveness of SBRT in cases of spinal metastatic cancer. The authors consider it prudent to routinely treat the pedicles and posterior elements using a wide bone margin posterior to the diseased vertebrae because of the possible direct extension into these structures. For patients without a history of radiotherapy, more liberal spinal cord dose constraints than those used in this study could be applied to help reduce failures in the epidural space.
Chang
Eric L
EL
Departments of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA. echang@mdanderson.org
Shiu
Almon S
AS
Mendel
Ehud
E
Mathews
Leni A
LA
Mahajan
Anita
A
Allen
Pamela K
PK
Weinberg
Jeffrey S
JS
Brown
Barry W
BW
Wang
Xin Shelly
XS
Woo
Shiao Y
SY
Cleeland
Charles
C
Maor
Moshe H
MH
Rhines
Laurence D
LD
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002637:Chest Pain / Q000209:etiology; D018450:Disease Progression; D004824:Epidural Space / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D005767:Gastrointestinal Diseases / Q000209:etiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011832:Radiation Injuries; D016634:Radiosurgery / Q000009:adverse effects; D013125:Spinal Neoplasms / Q000175:diagnosis / Q000556:secondary* / Q000601:surgery*; D016019:Survival Analysis; D014057:Tomography, X-Ray Computed; D017211:Treatment Failure; D016896:Treatment Outcome