Stereotactic Body Radiotherapy Is Effective Salvage Therapy for Patients With Prior Radiation of Spinal Metastases
Received 4 July 2008; received in revised form 13 September 2008; accepted 23 September 2008. published online 18 December 2008.
Purpose
To provide actuarial outcomes and dosimetric data for spinal/paraspinal metastases, with and without prior radiation, treated with stereotactic body radiotherapy (SBRT).
Methods and Materials
A total of 39 consecutive patients (60 metastases) were treated with SBRT between April 2003 and August 2006 and retrospectively reviewed. In all, 23 of 60 tumors had no previous radiation (unirradiated) and 37/60 tumors had previous irradiation (reirradiated). Of 37 reirradiated tumors, 31 were treated for “salvage” given image-based tumor progression. Local failure was defined as progression by imaging and/or clinically.
Results
At last follow-up, 19 patients were deceased. Median patient survival time measured was 21 months (95% CI = 8–27 months), and the 2-year survival probability was 45%. The median total dose prescribed was 24 Gy in three fractions prescribed to the 67% and 60% isodose for the unirradiated and reirradiated cohorts, respectively. The median tumor follow-up for the unirradiated and reirradiated group was 9 months (range, 1–26) and 7 months (range, 1-48) respectively. Eight of 60 tumors have progressed, and the 1- and 2-year progression-free probability (PFP) was 85% and 69%, respectively. For the salvage group the 1 year PFP was 96%. There was no significant difference in overall survival or PFP between the salvage reirradiated vs. all other tumors treated (p = 0.08 and p = 0.31, respectively). In six of eight failures the minimum distance from the tumor to the thecal sac was ≤1 mm. Of 60 tumors treated, 39 have ≥6 months follow-up and no radiation-induced myelopathy or radiculopathy has occurred.
Conclusion
Spine SBRT has shown preliminary efficacy and safety in patients with image-based progression of previously irradiated metastases.
∗Department of Radiation Oncology, University of California San Francisco, San Francisco, CA
†Department of Radiation Oncology, University of Toronto, Sunnybrook Odette Cancer Centre and the Princess Margaret Hospital, Toronto, ON, Canada
‡Department of Neurologic Surgery, University of California San Francisco, San Francisco, CA
§Department of Epidemiology, University of Toronto, Princess Margaret Hospital, Toronto, ON, Canada
‖Department of Radiology, University of California San Francisco, San Francisco, CA
¶UCSF Helen Diller Family Comprehensive Cancer Center Biostatistics Core, University of California San Francisco, San Francisco, CA
Reprint requests to: Dr. Arjun Sahgal, Department of Radiation Oncology, University of Toronto, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada. Tel: (416) 946-2131; Fax: (416) 480-6002
ABSTRACT