Posters— Radiation Oncology

TREATMENT OUTCOME IN PATIENTS RADIATED FOR SPINAL AND PARASPINAL TUMORS

DeLaney TF, Ancukiewicz M, Hornicek FJ, Spiro IJ, Harmon DC, Suit HD (Massachusetts General Hospital, Boston, MA 02114)

Objective: Tumors of the spine and paraspinal soft-tissues can present difficult management challenges because of the proximity of the spinal cord, which limits resection margins and radiation dosage. A retrospective review of treatment outcome in a cohort of these patients managed in a single institution was undertaken to assess prognostic factors and treatment techniques important for favorable treatment outcome.

Materials & Methods: 57 patients with spinal and paraspinal tumors treated with radiotherapy between 1971 and 1998 were identified in our sarcoma database. Nine patients with Ewing’s sarcoma/PNET were identified for separate analysis, leaving 48 patients for analysis for this study. Outcome was assessed according to the following tumor and treatment variables: site (spinal/paraspinal), tumor grade, surgical margin status, and radiation dose.

Results: Twenty-four lesions were in the spine and twenty-four were in paraspinal soft tissue. Forty-two patients had malignant tumors with the following histologies: neurofibrosarcoma/malignant schwannoma (9), malignant fibrous histiocytoma (7), chondrosarcoma (5), chordoma (5), osteosarcoma (4), fibrosarcoma (3), and others (9). Six patients had benign lesions: desmoid (2), giant cell tumor (2), aneurysmal bone cyst (1), and hemangioma (1). Median tumor size was 8.5 cm (range, 1.2-18 cm). Local treatment consisted of combined surgery and radiotherapy in forty-five patients and radiotherapy alone in 3 patients. Median radiation dose was 60.2 Gy (range 22.4-78.6 Gy). Five patients received brachytherapy as a component of treatment, with a median implant dose of 28.7 Gy while 2 patients received intra-operative radiotherapy. Chemotherapy was administered to fifteen patients. Overall five-year survival was dependent upon tumor grade: 0-1: 89%; 2: 48%; 3-4: 36%, p=0.10. Overall five-year survival was similar for spinal (72%) and paraspinal (63%) lesions, p=0.96. Local control was 85% for spinal lesions and 66% for paraspinal lesions, p=0.59. There was a trend towards improved local control in patients with negative surgical margins (81%) compared to patients in whom the margins were positive (55%), p=0.30. No clear relationship could be demonstrated between radiation dose and treatment outcome.

Conclusions: Similar to other sites, tumor grade is of prognostic importance in patients with spinal and paraspinal tumors. In spite of the large tumor size (median 8.5 cm) seen in this patient population and the limits on surgical resection and radiation dose imposed by proximity of the spinal cord, combined modality treatment with surgery and radiotherapy produced local control in the majority of patients. Improved therapeutic strategies are necessary for patients with positive surgical margins and paraspinal tumors, in whom local control remains suboptimal.