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.