Prognostic parameters for local control and survival after radiotherapy of stabilized bone metastases

Postoperative radiotherapy following surgical stabilization in patients with bone metastases is commonly recommended. The aim of the study was to validate existing prognostic scores and parameters for local control and survival in patients with bone metastases treated with surgical resection with or without radiotherapy.

This retrospective single-institution study analyzed consecutive patients with bone metastases undergoing resection and/or stabilization mostly due to pathologic or impending fractures (with or without spinal compression). Additive radiotherapy was considered the standard of care. Various fractionated radiotherapy regimens have been applied; equivalent dose in 2 Gy fractions (EQD2) has been calculated to enable comparison between fractionations. Prognostic factors influencing local progression-free survival (LPFS) and overall survival (OS) were evaluated.

The median follow-up was 9 months (range 1-121 months). A total of 142 patients were included. Most patients underwent surgery due to pathologic (n = 86, 60.6%) or impending fracture (n = 54, 38.0%), with or without spinal compression. Most common histologies were breast (n = 30, 21.1%) and lung cancer (n = 30, 21.1%); most common metastasis locations were spine (n = 58, 40.8%), lower (n = 56, 39.4%) and upper extremities (n = 23, 16.2%). Postoperative radiotherapy was performed in 89 patients (62.7%). Location in the spine and prior irradiation were identified as poor prognostic factors for LPFS. In patients with spine metastases, improved LPFS was demonstrated in those treated with postoperative radiotherapy (2 years LPFS 96.7% ± 3.3% vs. 23.4 ± 19.0%; p = 0.003). Postoperative radiotherapy did not improve LPFS in patients with bone metastases outside the spine (p = 0.960). Better OS rates were demonstrated in patients with good performance status (ECOG) and with moderate and good prognosis according to the Tokuhashi score.

Our real-life data revealed that a significant number of patients did not receive postoperative radiotherapy for various reasons. Established prognostic scores (Tokuhashi and ECOG score) correlate with patient survival, and their use should be encouraged to determine optimal patient treatment and to identify patients who may benefit from postoperative radiotherapy, due to their longer life expectancy. LPFS improved with postoperative radiotherapy in spinal bone metastases, but not in nonspinal metastases.