Spinal reirradiation after short-course RT for metastatic spinal cord compression

Purpose: To investigate the feasibility and effectiveness of reirradiation (re-RT) for in-field recurrence of metastatic spinal cord compression after primary RT with 1 × 8 Gy or 5 × 4 Gy. Methods and Materials: A total of 62 patients, treated with 1 × 8 Gy (n = 34) or 5 × 4 Gy (n = 28) between January 1995 and August 2003, received re-RT for in-field recurrence of metastatic spinal cord compression. The median time to recurrence was 6 months (range, 2-40 months). Re-RT was performed with 1 × 8 Gy (after 1 × 8 Gy or 5 × 4 Gy, n = 34), 5 × 3 Gy (after 1 × 8 Gy or 5 × 4 Gy, n = 15), or 5 × 4 Gy (after 1 × 8 Gy, n = 13). The cumulative biologically effective dose (primary RT plus re-RT) was 80-100 Gy₂. The median follow-up after re-RT was 8 months (range, 2-42 months). Motor function was evaluated up to 6 months after re-RT. Results: After re-RT, 25 patients (40%) showed improvement of motor function, 28 (45%) had no change, and 9 (15%) had deterioration. Of the 16 previously nonambulatory patients, 6 (38%) regained the ability to walk. No second in-field recurrence in the same spinal region was observed after re-RT. The outcome was not significantly influenced by the radiation schedule. Radiation myelopathy was not observed. Conclusions: Spinal re-RT with 1 × 8 Gy, 5 × 3 Gy, or 5 × 4 Gy for in-field recurrence of metastatic spinal cord compression appears safe and effective. Myelopathy seems unlikely, if the cumulative biologically effective dose is ≤100 Gy₂.