Results of a multicenter study investigating the potential impact of the overall treatment time on outcomes of radiation therapy alone with 5x4 Gy for metastatic epidural spinal cord compression

Purpose/Objective: A 5x4 Gy program is commonly used for metastatic epidural spinal cord compression (MESCC). It is unclear whether an overall treatment time (OTT) of 5 days (5 consecutive fractions) results in better outcomes than an OTT of 7 days (ie, no irradiation during the weekend). Methods and materials: A total of 111 patients who received 5x4 Gy over 5 consecutive days were retrospectively compared with 277 patients treated with 5x4 Gy over 7 days (no irradiation during the weekend) for effect on motor function, local control of MESCC, and overall survival (OS). Ten further characteristics were evaluated: age, gender, interval tumor diagnosis to MESCC, visceral metastases, other bone metastases, primary tumor type, time developing motor deficits, walking ability, vertebrae involved, and performance status. Results: On multivariate analysis regarding post-radiation therapy motor function, primary tumor type (P = .011) and time developing motor weakness (P < .001) were significant, whereas the OTT did not even achieve significance on univariate analysis (P = .99). On multivariate analysis of local control, visceral metastases (P = .006) were significant. Again, the OTT was not even significant on univariate analysis (P = .81). On multivariate analysis of OS, interval tumor diagnosis to MESCC (P = .015), visceral metastases (P = .001), tumor type (P = .003), walking ability (P < .001), and Eastern Cooperative Oncology Group performance score (P < .001) achieved significance. Even on univariate analysis, OTT did not have an effect on OS (P = .79). Conclusions: Longer OTT did not impair outcomes of irradiation with 5x4 Gy for MESCC; thus, no compensation (for example an additional radiation fraction) is necessary if the radiation treatment is not continued during the weekend. (C) 2016 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.