Dose escalation of radiotherapy for Metastatic Spinal Cord Compression (MSCC) in patients with relatively favorable survival prognosis

Abstract

Local control of metastatic spinal cord compression (MSCC) is particularly important for long-term survivors. Radiotherapy alone is the most common treatment for MSCC. The most frequently used schedule world wide is 30 Gy/10 fractions. This study investigated whether patients with favorable survival prognoses benefit from a dose escalation beyond 30 Gy. Data from 191 patients treated with 30 Gy/10 fractions were matched to 191 patients (1:1) receiving higher doses (37.5 Gy/15 fractions or 40 Gy/20 fractions). All patients had favorable survival prognoses based on a validated scoring system and were matched for age, gender, tumor type, performance status, number of involved vertebrae, visceral or other bone metastases, interval from tumor diagnosis to radiotherapy, ambulatory status, and time developing motor deficits. Both groups were compared for local control, progression-free survival, overall survival, and functional outcome. Local control rates at 2 years were 71% after 30 Gy and 92% after higher doses (p=0.012). Two-year progression-free survival rates were 68% and 90%, respectively (p=0.013). Two-year overall survival rates were 53% and 68%, respectively (p=0.032). Results maintained significance in the multivariate analyses (Cox proportional hazards model; stratified model) with respect to local control (p=0.011; p=0.012), progression-free survival (p=0.010; p=0.018), and overall survival (p=0.014; p=0.015). Functional outcome was similar in both groups. Motor function improved in 40% of patients after 30 Gy and 41% after higher doses (p=0.98). Escalation of the radiation dose beyond 30 Gy resulted in significantly better local control, progression-free survival, and overall survival in patients with favorable survival prognoses.