2895 - Low-Dose Radiation Therapy for Facetogenic Back Pain and Spondyloarthropathy: Early Results from a Prospective Cohort

Purpose/Objective(s): Facetogenic back pain and spondyloarthropathy represent significant sources of chronic pain with limited effective treatment options. Low-dose radiation therapy (LDRT) has demonstrated anti-inflammatory properties in benign conditions. Historical concerns regarding slight increased risk in hematopoietic malignancy in young men treated with high single-fraction orthovoltage therapy for ankylosing spondylitis have limited adoption. We report early results using modern fractionated techniques with conformal dose delivery.

Materials/Methods: Eleven patients with facetogenic back pain and/or spondyloarthropathy were treated with LDRT. Treatment sites included lumbar spine (n=6), cervical spine (n=4), and lumbosacral spine (n=2). Nine patients received 4.5 Gy in 10 fractions; two early patients received 3 Gy in 6 fractions. All patients were treated with 3D conformal arc-based or 4-field oblique box techniques. Dose heterogeneity was limited to 115%, with hotspots maintained outside the spinal canal. Pain was assessed using a 0-10 numeric rating scale for average, lowest, and worst pain before and after treatment. Response was defined as any reduction in average pain score.

Results: Among 9 patients with available post-treatment data, the overall response rate was 89% (8/9). Pre-treatment average pain ranged from 2.5-10 (mean 6.1), with worst pain of 5-10 (mean 8.5). Post-treatment average pain decreased to 0-6.5 (mean 3.3), representing a mean reduction of 2.8 points (46% improvement). Worst pain improved to 0-10 (mean 5.4), with mean reduction of 3.1 points (36% improvement). Four patients (44%) achieved post-treatment lowest pain scores of 0-1. The most dramatic response showed average pain decreasing from 5 to 0 after a single treatment cycle.

Conclusion: These preliminary results suggest LDRT may offer a promising therapeutic option for refractory facetogenic back pain and spondyloarthropathy. The 89% response rate and achievement of minimal pain in nearly half of patients warrant further investigation. Our approach differs substantially from historical ankylosing spondylitis treatments using high single-fraction whole-spine doses (6-12 Gy) with orthovoltage equipment, which demonstrated a slight signal for increased late malignancy risk. Modern fractionated regimens with conformal megavoltage techniques minimize collateral exposure while maintaining efficacy. Limitations include small sample size, short follow-up, lack of control group, and incomplete data for 2 patients. A larger prospective study with longer follow-up and standardized dosing is needed to validate these findings.