Postoperative Reirradiation Using Stereotactic Body Radiation Therapy for Metastatic Epidural Spinal Cord Compression: Selection of Eligible Cases

Abstract

This study aimed to clarify the outcomes of postoperative re-irradiation using stereotactic body radiotherapy (SBRT) for metastatic epidural spinal cord compression (MESCC), and to clarify factors correlated with local control. Patients with MESCC and a history of radiotherapy who had been treated with decompression surgery and spine SBRT were retrospectively reviewed. The prescribed dose for spine SBRT was 24 Gy in 2 fractions. Local control, ambulatory function and adverse events were evaluated. The correlation between local control and some factors including degree of compression, interval between last radiotherapy and SBRT, and prognostic scores were analyzed. Twenty-six patients were selected from our database: mean age, 63 years (range, 33-76); 18 men, 8 women; ECOG performance status 0-1/2/3, 17/7/2; lesion histopathology, thyroid/lung/renal/colorectal/other cancer, 7/6/3/3/7; mean interval since last irradiation, 25 months (range, 5-132). Median follow-up after SBRT was 14 months (range, 3-37). The 1-year local control rate was 73%. Bilsky grade, interval between last radiotherapy and SBRT, RPA and PRISM were not significantly correlated with local control. One-year local control of favorable survival prognosis group and intermediate/poor survival prognosis group by Rades score were 100% and 0% (p<.001). Comparing ambulatory functions between pre-treatment and 1 year after SBRT, improvement/no change/worsening was seen in 3/7/5 cases, respectively. Grade 3 acute and late adverse events were observed in 0 and 1 (myelopathy) patients. No grade 4 or greater toxicities were encountered. Spine SBRT appears meaningless as postoperative re-irradiation for patients with poor survival prognosis, and Rades score seems useful for selecting eligible cases.