Precision radiotherapy for metastatic spinal cord compression: Final results of the PRE-MODE Trial.Int J Radiat Oncol Biol Phys 2019IJ
To investigate precision radiotherapy for metastatic spinal cord compression (MSCC) and compare it to conventional radiotherapy.
METHODS AND MATERIALS
In a multi-center phase 2 study, 40 patients received 5Gyx5 of precision radiotherapy (38 volume modulated arc therapy, 2 intensity-modulated radiotherapy) for MSCC and were evaluated for local progression-free survival (LPFS), motor function, ambulatory status, sensory function, sphincter dysfunction, pain, distress, overall survival (OS) and toxicity. Maximum spinal cord dose was 101.5% (myelopathy risk <0.03%) of the prescription dose. Patients were compared to a historical control group conventionally irradiated with 4Gyx5 (propensity-score analysis). The equivalent dose in 2Gy-fractions of 5Gyx5 is similar to 3Gyx10, which results in better LPFS than 4Gyx5. It was assumed that 5Gyx5 is also superior to 4Gyx5 for LPFS. (ClinicalTrials.gov-identifier: XXX) RESULTS: Six-month rates of LPFS and OS were 95.0% and 42.6%, respectively. Improvement of motor function occurred in 24 patients (60%). Thirty-three patients (82.5%) were ambulatory following radiotherapy. Eight of 16 patients (50.0%) with sensory deficits improved. Pain and distress relief were reported by 61.9% and 54.2% of patients at 1 month following radiotherapy. Grade 3 toxicities occurred in one patient, grade 2 toxicities in another 3 patients. Of the control group, 664 patients qualified for the propensity-score analysis. 5Gyx5 was significantly superior to 4Gyx5 regarding LPFS (p=0.026), but not regarding motor function (p=0.51) or OS (p=0.82).
Precision radiotherapy with 5Gyx5 was well tolerated and effective, and appeared superior to 4Gyx5 regarding LPFS. The retrospective nature of the historic control group, which may have led to a hidden selection bias, needs to be considered when interpreting the results.