Introduction: 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). No other variable significantly correlated with progression-free survival, including radiation sensitivity of tumor histology, preoperative radiotherapy, grade of epidural spinal cord compression, extent of surgical decompression, or gender in multivariate analysis.
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%).
Patient Care: 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%).
Learning Objectives: By the conclusion of the session, participants should be able to evaluate the improvement in local disease control for spinal metastases following separation surgery and adjuvant hypofractionated or high-dose single-fraction radiation therapy.