Stereotactic Radiotherapy for Spinal Metastases in the Postoperative Setting : A Secondary Analysis of Mature Phase I-II Trials
Menée à partir des données de deux essais de phase I-II incluant au total 66 patients présentant des métastases spinales (durée médiane de suivi : 30 mois), cette étude évalue l'efficacité, du point de vue du contrôle tumoral et de la survie globale à 1 an, et la toxicité neurologique d'une radiothérapie corporelle stéréotaxique post-opératoire ciblant les métastases, puis identifie les facteurs pronostiques associés
Purpose : To evaluate the outcomes of patients treated on prospective phase I-II protocols with postoperative stereotactic body radiation therapy (SBRT) and identify the associated prognostic variables. Materials and Methods : Sixty-six patients with 69 tumors were treated with SBRT on two prospective phase I-II studies for spinal metastases between 2002 and 2010. All patients underwent SBRT after spine surgery, which included laminectomy, vertebrectomy, or a combination of these techniques. Renal cell carcinoma was the most common histology represented (n=35, 53%) followed by sarcomas (n=13, 20%). Thirty-one patients (47%) were treated with prior conventional radiation to the spine (median dose 30 Gy). Patients were followed with spinal MRI studies to determine the treated tumor control (TC). Pain and other symptom data were collected prospectively to determine treatment response and toxicity. Results : The median follow-up was 30 months (range, 1-145 months) for all patients and 75 months for living patients (range, 6-145 months). The actuarial 1-year rate of TC was 85%, adjacent vertebral body control was 85%, and overall survival (OS) was 74% (median 29 months). On multivariate competing risks analysis, sarcoma histology (SHR=2.38, 95% CI 1.05-5.6, P=.04) and larger preoperative tumor volumes (SHR=1.01, 95% CI 1.0-1.01, P=.006) were significantly associated with worse TC. KPS was the only significant predictor for OS on multivariate analysis. There were no differences in TC between patients treated with different surgical techniques or different preoperative or postoperative Bilsky grades. There were no grade 3 or higher neurologic toxicities. Conclusion : This study represents a large series of prospective data available on patients treated with SBRT in the postoperative setting. The combination of surgery with SBRT can offer patients with metastatic disease to the spine the chance of durable tumor control with minimal toxicity.