Phase II Study of High-Dose Photon/Proton Radiotherapy in the Management of Spine Sarcomas
Received 23 May 2008; received in revised form 25 August 2008; accepted 26 August 2008. published online 18 December 2008.
Purpose
Radiotherapy (XRT) for spine sarcomas is constrained by spinal cord, nerve, and viscera tolerance. Negative surgical margins are uncommon; hence, doses of ≥66 Gy are recommended. A Phase II clinical trial evaluated high-dose photon/proton XRT for spine sarcomas.
Methods and Materials
Eligible patients had nonmetastatic, thoracic, lumbar, and/or sacral spine/paraspinal sarcomas. Treatment included pre- and/or postoperative photon/proton XRT with or without radical resection; patients with osteosarcoma and Ewing's sarcoma received chemotherapy. Shrinking fields delivered 50.4 cobalt Gray equivalent (Gy RBE) to subclinical disease, 70.2 Gy RBE to microscopic disease in the tumor bed, and 77.4 Gy RBE to gross disease at 1.8 Gy RBE qd. Doses were reduced for radiosensitive histologies, concurrent chemoradiation, or when diabetes or autoimmune disease present. Spinal cord dose was limited to 63/54 Gy RBE to surface/center. Intraoperative boost doses of 7.5 to 10 Gy could be given by dural plaque.
Results
A total of 50 patients (29 chordoma, 14 chondrosarcoma, 7 other) underwent gross total (n = 25) or subtotal (n = 12) resection or biopsy (n = 13). With 48 month median follow-up, 5-year actuarial local control, recurrence-free survival, and overall survival are: 78%, 63%, and 87% respectively. Two of 36 (5.6%) patients treated for primary versus 7/14 (50%) for recurrent tumor developed local recurrence (p < 0.001). Five patients developed late radiation-associated complications; no myelopathy developed but three sacral neuropathies appeared after 77.12 to 77.4 Gy RBE.
Conclusions
Local control with this treatment is high in patients radiated at the time of primary presentation. Spinal cord dose constraints appear to be safe. Sacral nerves receiving 77.12-77.4 Gy RBE are at risk for late toxicity.
∗Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
†Department of Orthopedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA
‡Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
§Department of Medicine, Division of Hematology Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
‖Department of Biostatistics, Massachusetts General Hospital, Harvard Medical School, Boston, MA
¶Department of Surgery (Section of Surgical Oncology), Massachusetts General Hospital, Harvard Medical School, Boston, MA
Reprint requests to: Thomas F. DeLaney, M.D., Department of Radiation Oncology, Francis H. Burr Proton Therapy Center, Massachusetts General Hospital, 30 Fruit Street, Boston MA 02114. Tel: (617) 726-7869; Fax: (617) 724-9532
Presented at the 48th Annual Meeting of the American Society of Therapeutic Radiology and Oncology, November 5-9, 2006, Philadelphia, PA.
Conflict of interest: Dr. DeLaney has received honoraria from IBA Proton Therapy for speaking at Industry Sponsored Symposia on Proton Beam Radiotherapy.
ABSTRACT