Prognostic factors predicting functional outcomes, recurrence-free survival, and overall survival after radiotherapy for metastatic spinal cord compression in breast cancer patients

Purpose: To identify significant prognostic factors after irradiation of metastatic spinal cord compression (MSCC) in 335 breast cancer patients. Methods and Materials: The potential prognostic factors investigated included involved vertebra, other bone metastases, visceral metastases, performance status, pretreatment ambulatory status, time until motor deficits developed before RT, radiation schedule (shorter-course RT [one fraction of 8 Gy/five fractions of 4 Gy] vs. longer-course RT [10 fractions of 3 Gy/15 fractions of 2.5 Gy/20 fractions of 2 Gy), and the response to RT. Results: On multivariate analysis, better functional outcome was associated with slower development of motor deficits (p <0.001) and being ambulatory before RT (p <0.001). The overall recurrence rate of MSCC was greater if other bone metastases were present (p <0.001) and if shorter-course RT was used (p <0.001). In-field recurrences alone were more frequent after shorter-course RT (p = 0.008). Survival was negatively affected by the presence of visceral metastases (p <0.001), deterioration of motor function after RT (p <0.001), reduced performance status (p <0.001), and the rapid development of motor deficits (p = 0.044). Conclusion: Outcomes and survival after RT for MSCC in breast cancer patients are associated with several prognostic factors. Patients with poor expected survival may be treated with shorter-course RT to keep the overall treatment time short. If survival is expected to be relatively favorable, longer-course RT appears preferable, because it is associated with fewer MSCC recurrences.