Final results of a prospective study of the prognostic value of the time to develop motor deficits before irradiation in metastatic spinal cord compression

Purpose: Metastatic spinal cord compression often requires urgent treatment selection, which could be facilitated by strong prognostic factors. Because only the type of primary tumor and pretreatment ambulatory status are known as prognostic factors for functional outcome, we investigated the prognostic value of the time of motor deficit development before radiotherapy (RT). Methods and Materials: Ninety-eight patients were included between November 1998 and April 2000. Three subgroups were formed, according to time of motor deficit development before RT: 1-7 days (n = 31), 8-14 days (n = 31), and >14 days (n = 36). Ambulatory rates and motor function were evaluated for ≤24 weeks after RT. In a multivariate analysis, all three prognostic factors and radiation parameters were included. Results: In the >14-day subgroup, improvement occurred significantly (p < 0.001) more often than in the other subgroups (86% vs. 29% and 10%) and the posttreatment ambulatory rate was significantly higher (86% vs. 55% and 35%, p = 0.026). Multivariate analysis revealed the time of development of motor deficits before RT to be the strongest prognostic factor. Conclusion: Functional outcome is significantly better with slower development of motor deficits before RT. This new, independent, prognostic factor must be considered in future trials aiming to define an optimal RT schedule.