Prognostic factors for functional outcome and survival after reirradiation for in-field recurrences of metastatic spinal cord compression

The purpose of the current study was to retrospectively investigate clinical outcome and potential prognostic factors after reirradiation (Re-RT) for in-field recurrence of metastatic spinal cord compression (MSCC). Re-RT with 1 x 8 Gy (n = 48), 5 x 3 Gy (n = 29), 5 x 4 Gy (n = 30), 7 x 3 Gy (n = 3), 10-12 x 2 Gy (n = 11), or 17 x 1.8 Gy (n = 3) was administered to 124 patients. Cumulative biologically effective dose (BED) (first course of RT plus re-RT) ranged from 77.5 Gy(2) to 142.6 Gy(2), and was <or=120 Gy(2) in 114 (92%) patients. Twelve potential prognostic factors were investigated for associations with motor function and survival. Motor function improved in 45 (36%) patients, was stable in another 62 (50%) patients, and deteriorated in 17 (14%) patients. Upon multivariate analyses, the effect of Re-RT on motor function was significantly associated with the effect of the first course of RT (P = .048), Eastern Cooperative Oncology Group (ECOG) performance status (P = .020), time to development of motor deficits before Re-RT (P = .002), and visceral metastases (P <.001). Survival was associated with ECOG performance status (P <.001), ambulatory status before Re-RT (P <.001), time to development of motor deficits (P = .018), and visceral metastases (P <.001). Re-RT dose schedule or cumulative BED had no significant impact on functional outcome or survival. Acute toxicity was mild, and late toxicity, such as radiation myelopathy, was not observed. Given the limitations of a retrospective study and the relatively short follow up after Re-RT, spinal reirradiation appeared to be effective and safe when the cumulative BED is </=120 Gy(2). Motor function after Re-RT was associated with the effect of first irradiation, performance status, time to development of motor deficits, and visceral metastases, whereas the Re-RT schedule had no significant impact