Low-dose radiation therapy for peripheral joint osteoarthritis: Early U.S. community experience with pain, function, and medication outcomes.

e24051 Background: Osteoarthritis (OA) causes progressive pain and disability, yet non-surgical options are limited for patients who cannot tolerate long-term NSAIDs or opioids. European data suggest that low-dose radiotherapy (LDRT) may alleviate inflammatory pain, but U.S. outcomes remain largely unreported. This retrospective study evaluated pain, function, and medication trends following LDRT delivered in community oncology settings. Methods: Thirty patients (55 joints) with mild-to-moderate OA received LDRT (3 Gy in 6 fractions, 0.5 Gy/fraction) between 2023–2025. Pain was measured by the Numeric Rating Scale (NRS 0–10) and functional improvement by the von Pannewitz Score (VPS 0–4, lower = greater improvement). Analgesic use changes were recorded at 1–3 months post-therapy. The primary endpoint was change in NRS; secondary endpoints were ≥2-point or ≥30% NRS improvement, VPS ≤ 1, and reduction in analgesic use. Paired t-tests and descriptive statistics were applied (α = 0.05). Results: Mean baseline NRS 8.1 ± 1.4 improved to 3.5 ± 1.7 (Δ – 4.6; p < 0.001). Twenty-five of 30 patients (83%) achieved a clinically meaningful NRS reduction (≥2 points or ≥30% improvement). Ninety-two percent of treated joints showed functional improvement (VPS ≤ 1). Twenty-three percent decreased analgesic use, and none required escalation. No acute or late toxicity occurred. Clinical response correlated with baseline pain intensity but not age or joint site. Conclusions: Community-based LDRT for peripheral joint OA was feasible, safe, and associated with significant, clinically meaningful reductions in pain and analgesic use. These findings parallel emerging randomized European data and support LDRT as a promising non-invasive adjunct for chronic OA pain. Prospective multicenter studies are warranted to confirm durability and optimize dose selection. Pain and analgesic outcomes following LDRT (n = 30 patients, 55 joints). Measure Baseline Follow-Up Change / Result NRS (0–10) 8.1 ± 1.4 3.5 ± 1.7 Δ – 4.6, p < 0.001 ≥ 2-point NRS improvement (%) – 83 – VPS improved (%) – 92 – Analgesic use decreased (%) – 23 7 / 30 patients Analgesic escalation (%) – 0 None Values represent 1–3-month follow-up; significance by paired t-test.