Comparison of 5 × 5 Gy and 10 × 3 Gy for metastatic spinal cord compression using data from three prospective trials.

BACKGROUND: In a palliative situation like metastatic spinal cord compression (MSCC), overall treatment time of radiotherapy should be as short as possible. This study compared 5 × 5 Gy in 1 week to 10 × 3 Gy in 2 weeks in a prospective cohort. METHODS: Forty patients receiving 5 × 5 Gy in a phase II trial were matched 1:2 to 213 patients receiving 10 × 3 Gy in two previous prospective studies for tumor type, ambulatory status, time developing motor deficits, interval between tumor diagnosis and MSCC and visceral metastases. These factors were consistent in all three patients (triple) used for each 1:2 matching. Groups were compared for local progression-free survival (LPFS), motor function, ambulatory status, and overall survival (OS). RESULTS: After matching, 32 triples remained for analyses (N = 96 in total). Six-month LPFS-rates were 94% after 5 × 5 Gy and 87% after 10 × 3 Gy (p = 0.36), 6-month OS-rates 43% and 35% (p = 0.74). Improvement of motor function was achieved in 59% and 34% of patients (p = 0.028); overall response rates (improvement or no further progression of motor deficits) were 94% and 89% (p = 0.71). Post-treatment ambulatory rates were 81% after 5 × 5 Gy and 85% after 10 × 3 Gy (p = 0.61). Of non-ambulatory patients, 50% (6/12) and 46% (11/24) regained the ability to walk (p = 1.00). CONCLUSIONS: 5 × 5 Gy in 1 week appeared similarly effective as 10 × 3 Gy in 2 weeks. These results may not be applicable to long-term survivors and should be confirmed in a randomized trial directly comparing 5 × 5 Gy and 10 × 3 Gy. Trial registration clinicaltrials.gov NCT03070431. Registered 27 February 2017.

Precision Radiation Therapy for Metastatic Spinal Cord Compression: Final Results of the PRE-MODE Trial.

OBJECTIVE: To investigate precision radiation therapy for metastatic spinal cord compression and compare it to conventional radiation therapy. METHODS AND MATERIALS: In a multicenter phase 2 study, 40 patients received 5 Gy × 5 fractions of precision radiation therapy (38 volume modulated arc therapy, 2 intensity modulated radiation therapy) for metastatic spinal cord compression 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 with a historical control group conventionally irradiated with 4 Gy × 5 fractions (propensity score analysis). The equivalent dose in 2 Gy-fractions of 5 Gy × 5 fractions is similar to 3 Gy × 10 fractions, which results in better LPFS than 4 Gy × 5 fractions. It was assumed that 5 Gy × 5 fractions is also superior to 4 Gy × 5 fractions for LPFS. (ClinicalTrials.gov-identifier: NCT03070431) 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 after radiation therapy. Eight of 16 patients (50.0%) with sensory deficits improved. Pain and distress relief were reported by 61.9% and 54.2% of patients 1 month after radiation therapy. Grade 3 toxicities occurred in 1 patient and grade 2 toxicities in another 3 patients. Of the control group, 664 patients qualified for the propensity score analysis; 5 Gy × 5 fractions was significantly superior to 4 Gy × 5 fractions with regard to LPFS (P = .026) but not motor function (P = .51) or OS (P = .82). CONCLUSIONS: Precision radiation therapy with 5 Gy × 5 fractions was well tolerated and effective and appeared superior to 4 Gy × 5 fractions in terms of LPFS. The retrospective nature of the historic control group, which might have led to a hidden selection bias, needs to be considered when interpreting the results.