Recursive partitioning analysis is predictive of overall survival for patients undergoing spine stereotactic radiosurgery.

Spine stereotactic radiosurgery (SRS) offers excellent radiographic and pain control for patients with spine metastases. We created a prognostic index using recursive partitioning analysis (RPA) to allow better patient selection for spine SRS. Patients who underwent single-fraction spine SRS for spine metastases were included. Primary histologies were divided into favorable (breast/prostate), radioresistant (renal cell/sarcoma/melanoma) and other. Cox proportional hazards regression was done to identify factors associated with overall survival (OS). RPA was performed to identify factors to classify patients into distinct risk groups with respect to OS. A total of 444 patients were eligible. Median dose was 16 Gy (range 8-18) in 1 fraction and median follow-up was 11.7 months. At time of analysis, 103 (23.1%) patients were alive. Median OS was 12.9 months. RPA identified three distinct classes. Class 1 was defined as KPS > 70 with controlled systemic disease (n = 142); class 3 was defined as KPS ≤ 70 and age < 54 years or KPS ≤ 70 age ≥ 54 years and presence of visceral metastases (n = 95); all remaining patients comprise class 2 (n = 207). Median overall survival was 26.7 months for class 1, 13.4 months for class 2, and 4.5 months for class 3 (p < 0.01). Our analysis demonstrates that there is considerably variability in survival among patients undergoing spine SRS. We created an objective risk stratification via RPA for spine SRS. Given the safety and efficacy of spine SRS and good survival in class 1 and 2 patients, this RPA can help clinicians identify patients who may benefit from upfront spine SRS.

Recursive partitioning analysis index is predictive for overall survival in patients undergoing spine stereotactic body radiation therapy for spinal metastases.

PURPOSE: To generate a prognostic index using recursive partitioning analysis (RPA) for patients undergoing spine stereotactic body radiation therapy (sSBRT) for spinal metastases (sMet). METHODS & MATERIALS: From an institutional review board-approved database, 174 patients were treated for sMet with sSBRT between February 2006 and August 2009. Median dose was 14 Gy (range, 8-24 Gy), typically in a single fraction (range, 1-5). Kaplan-Meier analysis was performed to detect any correlation between survival and histology. Histologies were divided into favorable (breast and prostate), radioresistant (renal cell, melanoma and sarcoma), and other (all other histologies). RPA was performed to identify any association of the following variables with overall survival (OS) following sSBRT: histology, gender, age, Karnofsky performance status (KPS), control of primary, extraosseous metastases, time from primary diagnosis (TPD), dose of sSBRT (≤14 Gy vs. >14 Gy), extent of spine disease (epidural only, bone and epidural, bone only), upfront or salvage treatment, presence of paraspinal extension, and previous surgery. RESULTS: Median follow-up was 8.9 months. Median OS time from sSBRT was 10.7 months. Median OS intervals for favorable histologies were 14 months, 11.2 months for radioresistant histologies, and 7.3 months for other histologies (p = 0.02). RPA analysis resulted in three classes (p < 0.0001). Class 1 was defined as TPD of >30 months and KPS of >70; Class 2 was TPD of >30 months and KPS of ≤70 or a TPD of ≤30 months and age <70 years old; Class 3 was TPD of ≤30 months and age ≥70 years old. Median OS was 21.1 months for Class 1 (n = 59), 8.7 months for Class 2 (n = 104), and 2.4 months for Class 3 (n = 11). CONCLUSION: sSBRT patients treated for sMet have a wide variability in OS. We developed an RPA classification system that is predictive of OS. While many patients are treated for palliation of pain or to avoid symptomatic progression, this index may be used to predict which patients may benefit most from sSBRT.