Local control and patterns of failure for “Radioresistant” spinal metastases following stereotactic body radiotherapy compared to a “Radiosensitive” reference

Cancer shared this article with you from Inoreader Local control and patterns of failure for "Radioresistant" spinal metastases following stereotactic body radiotherapy compared to a "Radiosensitive" reference Via Latest Results for Journal of Neuro-Oncology Abstract Purpose The concept of a radioresistant (RR) phenotype has been challenged with use of stereotactic body radiotherapy (SBRT). We compared outcomes following SBRT to RR spinal metastases to a radiosensitive cohort. Methods Renal cell, melanoma, sarcoma, gastro-intestinal, and thyroid spinal metastases were identified as RR and prostate cancer (PCA) as radiosensitive. The primary endpoint was MRI-based local failure (LF). Secondary endpoints included overall survival (OS) and vertebral compression fracture (VCF). Results From a prospectively maintained database of 1394 spinal segments in 605 patients treated with spine SBRT, 173 patients/395 RR spinal segments were compared to 94 patients/185 PCA segments. Most received 24–28 Gy in 2 fractions (68.9%) and median follow-up was 15.5 months (range, 1.4–84.2 months). 1- and 2-year LF rates were 19.2% and 22.4% for RR metastases, respectively, which were significantly greater (p < 0.001) than PCA (3.2% and 8.4%, respectively). Epidural disease (HR: 2.47, 95% CI 1.65–3.71, p < 0.001) and RR histology (HR: 2.41, 95% CI 1.45–3.99, p < 0.001) predicted for greater LF. Median OS was 17.4 and 61.0 months for RR and PCA cohorts, respectively. Lung/liver metastases, polymetastatic disease and epidural disease predicted for worse OS. 2-year VCF rates were ~ 13% in both cohorts. Coverage of the CTV V90 (clinical target volume receiving 90% of prescription dose) by ≥ 87% (HR: 2.32, 95% CI 1.29–4.18, p = 0.005), no prior spine radiotherapy (HR: 1.96, 95% CI 1.09–3.55, p = 0.025), and a greater Spinal Instability Neoplasia Score (p = 0.013) predicted for VCF. Conclusions Higher rates of LF were observed after spine SBRT in RR metastases. Optimization strategies include dose escalation and aggressive management of epidural disease. View on the web Inoreader. Take back control of your news feed. Follow us on Twitter and Facebook.