Results of a multicenter study investigating the potential impact of the overall treatment time on outcomes of radiation therapy alone with 5×4 Gy for metastatic epidural spinal cord compression

Purpose/Objective A 5×4 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 5×4 Gy over 5 consecutive days were retrospectively compared with 277 patients treated with 5×4 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 5×4 Gy for MESCC; thus, no compensation (for example an additional radiation fraction) is necessary if the radiation treatment is not continued during the weekend.