Local disease control for spinal metastases following “separation surgery” and adjuvant hypofractionated or high-dose single-fraction stereotactic radiosurgery: outcome analysis in 186 patients

Abstract

OBJECT Decompression surgery followed by adjuvant radiotherapy is an effective therapy for preservation or recovery of neurologic function and achieving durable local disease control in patients suffering from metastatic epidural spinal cord compression. The authors examine the outcomes of postoperative image-guided intensity-modulated radiation therapy (IG-IMRT) delivered as single-fraction or hypofractionated stereotactic radiosurgery (SRS) for achieving long-term local tumor control. METHODS A retrospective chart review identified 186 patients with epidural spinal cord compression from spinal metastases who were treated with surgical decompression, instrumentation, and postoperative radiation delivered as either single-fraction SRS (24 Gy) in 40 patients (22%), high-dose hypofractionated SRS (24-30 Gy in 3 fractions) in 37 patients (20%), or low-dose hypofractionated SRS (18-36 Gy in 5 or 6 fractions) in 109 patients (58%). The relationships between postoperative adjuvant SRS dosing and fractionation, patient characteristics, tumor histology-specific radiosensitivity, grade of epidural spinal cord compression, extent of surgical decompression, response to preoperative radiotherapy, and local tumor control were evaluated by competing risks analysis. RESULTS The total cumulative incidence of local progression was 16.4% one year after SRS. Multivariate Gray’s competing risks analysis revealed a significant improvement in local control with high-dose hypofractionated SRS (4.1% cumulative incidence of local progression at 1 year; hazard ratio = 0.12, p = 0.04) as compared to low-dose hypofractionated SRS (22.6% local progression at 1 year; HR = 1). Although univariate analysis demonstrated a trend towards greater risk of local progression for patients that failed preoperative cEBRT (22.2% local progression at 1 year, HR = 1.96, p = 0.07) compared to patients who did not receive any preoperative radiotherapy (11.2% local progression at 1 year, HR = 1), this association was not confirmed with multivariate analysis. No other variable significantly correlated with progression-free survival, including radiation sensitivity of tumor histology, grade of epidural spinal cord compression, extent of surgical decompression, or gender. CONCLUSIONS Postoperative adjuvant SRS following epidural spinal cord decompression and instrumentation is a safe and effective strategy for establishing durable local tumor control regardless of tumor histology-specific radiosensitivity. Patients who received high-dose hypofractionated SRS demonstrated one-year local progression rates less than 5% (95% CI: 0-12.2%), which were superior to the results of low-dose hypofractionated SRS. The local progression rate after single-fraction SRS was less than 10% (95% CI: 0-19.0%).

Spinal metastases: From conventional fractionated radiotherapy to single-dose SBRT

“…Recently, Laufer et al retrospectively reviewed the outcomes of 186 patients suffering from metastatic epidural spinal cord compression treated with surgical decompression, instrumentation, and postoperative IGRT delivered as either single-dose of 24 Gy (40/186; 21.5%), high-dose hypofractionation in 3 fractions and a total dose of 24-30 Gy (37/186; 19.9%), or low-dose hypofractionation in 5 or 6 fractions and a total dose of 18-36 Gy (109/186; 58.6%). 38 The overall local progression rate after radiation was 16% at 1 year. The only factor significantly associated with local tumor progression was the post-operative radiation dose, with the high-dose hypofractionated regimen resulting in a 4% local progression rate after 1 year, compared with the significantly higher 1-year local progression rate of 22% for the low-dose hypofractionated approach.…”

Stereotactic radiosurgery and immunotherapy for metastatic spinal melanoma

“…50 The goal of separation surgery is to decompress epidural tumor from a posterolateral approach to circumferentially decompress the spinal cord and reconstitute the thecal sac, followed by long posterior segmental fixation (e.g., with pedicle screws) to provide immediate stability. 43 Following surgery, patients undergo high-dose single-fraction or hypofractionated radiation to Data show that spinal decompression surgery followed by cEBRT results in significantly better survival times and overall ambulation than cEBRT alone, with no significant difference in hospitalization time. 60 However, the radioresistance of melanoma to cEBRT results in high local recurrence rates when used as a postoperative adjuvant.…”

Variability in Spine Radiosurgery Treatment Planning -- Results of an International Multi-institutional Study

“…Spine Stereotactic Radiosurgery (SRS), sometimes also referred to as Stereotactic Body Radiation Therapy (SBRT) to the spine, has been demonstrated to result in promising long term local control and pain palliation with low toxicity rates [11][12][13][14][15][16]. The use of SRS as an alternative treatment to conventional RT has been increasing rapidly.…”