Radiotherapy with 5 × 5 Gy for Personalized Treatment of Malignant Epidural Compression of the Myelon: Long-Term Results of the PRE-MODE Trial

Background/Objectives: Despite increasing use of upfront decompressive surgery for malignant epidural compression of the myelon (MESCC), a substantial number of affected patients still receive radiotherapy (RT) alone. Many of these patients would benefit from a personalized treatment approach including the most appropriate dose-fractionation regimen. The PRE-MODE trial (NCT03070431) compared precision RT with 5 × 5 Gy (prospective cohort, n = 40) to conventional RT with 5 × 4 Gy (historical control, n = 676)). After propensity-score matching, 5 × 5 Gy resulted in significantly increased local progression-free survival (LPFS) at 6 months than 5 × 4 Gy. The question arose whether this benefit is still present after a longer period of follow-up. Methods: For this additional study, supplementary data were retrospectively captured, resulting in prolongation of follow-up until 24 months. Results: 5 × 5 Gy resulted in LPFS of 80.9% at each investigated time point (12, 18, and 24 months) without reported radiation myelopathy. Moreover, 5 × 5 Gy showed a trend towards improved LPFS after 12 (p = 0.070), 18 (p = 0.060), and 24 (p = 0.054) months. Similarly to the original PRE-MODE trial, OS-rates were not significantly different in the dose groups of this supplementary study. Conclusion: Since 5 × 5 Gy resulted in excellent long-term LPFS and showed a trend towards better outcomes up to 24 months following RT, it appears preferable to 5 × 4 Gy and will contribute to the personalized treatment of patients with MESCC who are assigned to RT alone without upfront neurosurgical intervention.