Stereotactic Body Radiation Therapy for Spinal Metastases; Clinical Experience in 134 Cases from a Single Japanese Institution

Abstract

This study aimed to clarify the outcomes of stereotactic body radiotherapy (SBRT) for spinal metastases in our institution. Patients treated with spine SBRT were retrospectively reviewed from a prospective database. The prescribed dose was 24 Gy in 2 fractions. Endpoints were local control, pain control, and adverse events. Local control was defined as elimination, shrinkage, or no change in tumor on computed tomography or magnetic resonance imaging. Pain status was measured on a scale of 0-10 by patient's self-reports, and pain response was defined as the time at which pain scale score decreased by more than 2 from the baseline score without increase in analgesics. In addition, various treatment- and tumor-specific factors were evaluated to determine predictive values for local and pain control. This study included 134 lesions in 131 patients, with: histology of primary disease, lung/colorectal/thyroid/renal/breast/prostate/sarcoma/other cancer, 24/22/18/14/12/10/6/25; re-irradiation SBRT, 82 cases (61.2%); and postoperative SBRT for epidural spinal cord compression, 45 cases (33.6%). Median follow-up after SBRT was 9 months (range, 1-50 months). The 1-year local control rate was 72.3%. Seventy of the 88 cases (79.5%) with pain from spinal metastases achieved pain response after SBRT. The 1-year pain progression-free rate was 61.7%. Regarding colorectal metastases, local and pain control rates at 1 year were significantly lower compared with other cancer types (local control rate, 33.8% vs. 75.4%, p<0.01; pain progression-free rate, 36.9% vs. 70.2%, p=0.04). On multivariate analysis, colorectal metastases and radiation history were identified as independent predictors of lower local and pain control rates. Radiation-induced myelopathy, radiculopathy and vertebral compression fractures were observed in 0, 2 (1.5%) and 16 (11.9%) cases, respectively. No other grade 3 or greater toxicities were encountered. The present study showed that spine SBRT achieved good local and pain control, and a clinically acceptable safety profile. However, SBRT may be less effective against colorectal metastases.Abstract TU_15_3037; Table 1Characteristics (Number of cases)1-y radiographic local control rateUnivariate P valueMultivariate analysisP valueHR95% CIKarnofsky PS 80+ (105) <80 (26)73.9% 64.3%0.27NANANAHistopathology Colorectal (22) Thyroid (20) Renal cell (14) Sarcoma (6) Melanoma (0) Other (72)34.1% 80.8% 88.9% Not reached No Data 82.5%<0.01*<0.01*3.911.77 to 8.64Systemic disease Controlled (71) Active (63)75.6% 68.3%0.48NANANANumber of spinal levels 1 (61) 2 (24) 3 or more (31)72.9% 83.3% 67%0.70NANANARadiation history Radiation naïve (52) Prior spine radiation (81)84.7% 61.6%0.02*0.04*0.420.18 to 0.95Surgical decompression - (89) + (45)71.4% 73.3%0.57NANANABilsky grade at SBRT 0/I (98) II/III (36)77.5% 60.6%0.28NANANA Open table in a new tab