Main Session
Sep
28
SS 17 - Emerging Data for Use of Radiotherapy in Nonmalignant Conditions
188 - Patient Reported Outcomes Following Low-Dose Irradiation for Osteoarthritis (PRO-LO): A Single-Arm Prospective Observational Cohort Study
Presenter(s)
Victoria Xu, BS - University of North Carolina at Chapel Hill, Chapel Hill, NC
V. Xu1, M. Regan2, O. Morton1, P. Bramblett1, R. Silva1, X. Tan3, A. Kovacik4, A. Wijetunga5, C. Shen1, K. A. Pearlstein5, J. Hall6, and T. K. Yanagihara7; 1Department of Radiation Oncology, University of North Carolina, Chapel Hill, NC, 2University of North Carolina School of Medicine, Providence, NC, United States, 3Gillings School of Global public health, University of North Carolina, Chapel Hill, NC, 4Department of Radiation Oncology, University of North Carolina School of Medicine, Chapel Hill, NC, 5University of North Carolina, Chapel Hill, NC, 6VCU School of Medicine, Richmond, VA, 7University of North Carolina, Department of Radiation Oncology, Chapel Hill, NC
Purpose/Objective(s):
Low-dose radiotherapy (LDRT) is an emerging treatment option in the management of osteoarthritis (OA)-related pain, but its utilization in the U.S. remains limited and its effects on joint function are not well studied. This prospective cohort study evaluated pain scores and joint-specific patient-reported functional outcomes following LDRT for OA in a U.S. population.Materials/Methods:
This single-institution, single-arm study, enrolled patients >55 years old with non-shoulder, non-spine OA that failed at least two prior treatment modalities and had a visual analog pain scale (VAPS, scored from 0 - 10) score >4. The primary endpoint was change in VAPS at 3-months with the hypothesis that LDRT would improve VAPS by >3 points. Treatment was 300 cGy over six every-other-day fractions with opposed photon fields. VAPS scores, pain-medication use, and joint-specific functional assessments were collected with validated patient-reported questionnaires, such as the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. Toxicities were assessed using CTCAE v5.0.Results:
Between 7/2023 – 7/2025, 40 patients were enrolled (32 women, median 71.5 years old). One patient enrolled, but was treated at another facility and excluded from analyses. Among the 39 patients who had at least one course of LDRT, 14 (36%) underwent at least one re-treatment and 24 (62%) were treated to more than one joint simultaneously (e.g., bilateral). Excluding re-treatments, a total of 68 joints received LDRT. The majority of patients were treated to the knee (n=34), followed by foot (n=5), hand (n=3), and hip (n=2). Pain scores decreased across all joint types. For the overall cohort, the median change in maximum daily VAPS (maximum pain score in a day) at 6-weeks and 3-months after LDRT was -3 and -3, respectively. The median change in average daily VAPS (average reported pain score in a day) was -3 and -2, at 6-weeks and 3-months, respectively. In patients with knee OA, functional assessments demonstrated improvements at both 6-weeks and 3-months of follow-up. The largest subgroup (n=47 joints), reported a median improvement in KOOS of 12 points, representing an median change from moderate-severe dysfunction (score=39) to mild-moderate dysfunction (score=51) at 6-weeks, and this was maintained at 3-months (score=49). There were no grade >2 adverse events attributed to LDRT. One patient (3%) reported grade 1 lymphedema and one patient reported grade 1 fatigue, although neither was considered likely related to RT.Conclusion:
This study met its primary endpoint of a >3 point improvement in maximum VAPS 3-months after LDRT. LDRT was associated with clinically meaningful pain reductions across all treated joints with essentially no adverse events. Placebo controlled studies with long-term follow-up, quality of life measures, and cost comparisons with other OA modalities are warranted.