Incidence and severity of adverse events associated with re-irradiation for spine or pelvic bone metastases.

Abstract

Adverse events associated with re-irradiation for painful bone metastases have not been adequately evaluated. The purpose of this study was to clarify the incidence and severity of adverse events associated with re-irradiation for spine or pelvic bone metastases. Data for 61 consecutive patients who required re-irradiation for spine or pelvic bone metastases between April 2009 and March 2013 were retrospectively evaluated in this study. The adverse events, biologically effective dose (BED), and the responses to pain and/or symptoms caused by cord compression were evaluated. Of the 61 patients, 52 were included in the study and their data were analyzed. The site of re-irradiation was the spine in 35 patients (67%), and the pelvic bone in the remaining 17 patients (33%). The median follow-up period was 170days (range 5-1,644days) for all eligible patients. The median interval from initial radiation therapy to re-irradiation was 161days (range 26-2,909days). The median cumulative BED from the initial radiation and re-irradiation was 115Gy (range 80-155Gy2). The acute adverse events were all below grade 2 in severity, except for two patients who showed grade 3 pain flare within a few days after the start of re-irradiation. No late adverse events were observed in this study that were grade 3 or of worse severity. The incidence and severity of adverse events after re-irradiation for spine or pelvic bone metastases were within acceptable limits in this study.