Ori Barzilai, Natalie DiStefano, Eric Lis, Yoshiya Yamada, D. Michael Lovelock, Andrew N. Fontanella, Mark H. Bilsky and Ilya Laufer
The aim of this study was to evaluate the safety and efficacy of kyphoplasty treatment prior to spine stereotactic radiosurgery (SRS) in patients with spine metastases.
A retrospective review of charts, radiology reports, and images was performed for all patients who received SRS (single fraction; either standalone or post-kyphoplasty) at a large tertiary cancer center between January 2012 and July 2015. Patient and tumor variables were documented, as well as treatment planning data and dosimetry. To measure the photon scatter due to polymethyl methacrylate, megavolt photon beam attenuation was determined experimentally as it passed through a kyphoplasty cement phantom. Corrected electron density values were recalculated and compared with uncorrected values.
Of 192 treatment levels in 164 unique patients who underwent single-fraction SRS, 17 (8.8%) were treated with kyphoplasty prior to radiation delivery to the index level. The median time from kyphoplasty to SRS was 22 days. Four of 192 treatments (2%) demonstrated local tumor recurrence or progression at the time of analysis. Of the 4 local failures, 1 patient had kyphoplasty prior to SRS. This recurrence occurred 18 months after SRS in the setting of widespread systemic disease and spinal tumor progression. Dosimetric review demonstrated a lower than average treatment dose for this case compared with the rest of the cohort. There were no significant differences in dosimetry analysis between the group of patients who underwent kyphoplasty prior to SRS and the remaining patients in the cohort. A preliminary analysis of polymethyl methacrylate showed that dosimetric errors due to uncorrected electron density values were insignificant.
In cases without epidural spinal cord compression, stabilization with cement augmentation prior to SRS is safe and does not alter the efficacy of the radiation or preclude physicians from adhering to SRS planning and contouring guidelines.
Ibrahim Hussain, Ori Barzilai, Anne S. Reiner, Lily McLaughlin, Natalie M. DiStefano, Shahiba Ogilvie, Anne L. Versteeg, Charles G. Fisher, Mark H. Bilsky and Ilya Laufer
The Spinal Instability Neoplastic Score (SINS) correlates with preoperative disability and response to stabilization, with patients with higher scores experiencing greater relief after surgery. However, there is a paucity of data demonstrating the extent to which each component contributes to preoperative clinical status and response to stabilization surgery. The objectives of this study were 2-fold. First, to determine how SINS components correlate with pre- and postoperative patient-reported outcomes (PROs). Second, to determine whether patients with higher SINS (10–12) in the “indeterminate” group respond differently to surgery compared to patients with lower SINS (7–9).
SINS and PROs were prospectively collected in 131 patients undergoing stabilization surgery for metastatic spinal disease. Association of SINS components and their individual scores with preoperative symptom burden and PRO symptom change after surgery was analyzed using the Spearman rank correlation coefficient (rho) and the Kruskal-Wallis test. SINS and association with preoperative PRO scores and mean differences in post- and preoperative PRO scores were compared for 2 SINS categories within the indeterminate group (7–9 vs 10–12) using the Wilcoxon 2-sample test and Wilcoxon signed-rank test.
The presence of mechanical pain, followed by metastatic location, correlated most strongly with preoperative functional disability measures and lower disability PRO scores following surgical stabilization. Blastic rather than lytic bone lesions demonstrated stronger association with pain reduction following stabilization. Following surgery, patients with SINS 10–12 demonstrated markedly greater improvement in pain and disability PRO scores nearly across the board compared to patients with SINS 7–9.
The presence of mechanical pain has the strongest correlation with preoperative disability and improvement in pain and disability PRO scores after surgery. Radiographic components of SINS also correlate with preoperative symptom severity and postoperative PRO, supporting their utilization in evaluation of spinal instability. Among patients with indeterminate SINS, patients with higher scores experience greater reduction in pain and disability PRO scores following surgical stabilization, suggesting that the indeterminate-SINS group includes distinct populations.