249 - Interim Analysis of Mitigating Osteoarthritis by Intervention with Low-Dose Irradiation to Extremities (MOBILE)
Presenter(s)
H. F. Byrd1, A. Dove1, S. R. Katz2, L. R. Rosen2, C. J. Wang2, B. J. Ager3, C. D. Jacobs4, R. M. Whitaker1, A. Shinde1, A. J. Cmelak1, Z. A. Kohutek1, N. B. Newman5, and A. N. Kirschner1; 1Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN, 2Willis-Knighton Cancer Center, Shreveport, LA, 3Cancer Care Northwest, Spokane, WA, 4Kootenai Clinic Cancer Services, Coeur D'alen, ID, 5UT Health San Antonio, Mays Cancer Center, San Antonio, TX
Purpose/Objective(s): Osteoarthritis (OA) is a widespread, debilitating, and costly condition affecting millions of Americans. Current treatment options primarily focus on symptom relief, ranging from oral analgesics and steroidal injections to joint replacement surgery. Low-dose radiotherapy (LDRT) represents an underutilized treatment modality with proven benefits in managing OA symptoms. MOBILE is an ongoing multi-institutional prospective observational study evaluating the feasibility of integrating LDRT for OA into radiotherapy practices in the U.S.
Materials/Methods: Patients diagnosed with OA of an extremity were eligible for LDRT, receiving 3 Gy in 6 fractions on nonconsecutive days over a 14-day period. Primary endpoints included pain relief, treatment-related toxicity, and OA-related medication usage. These were assessed pre-treatment and post-treatment at 6 weeks, 3 months, and 6 months using the Visual Analogue Pain Scale (VAS) (0, no pain; 10, strongest pain) and Von Pannewitz Score (VPS) (0, symptom-free;1, significantly improved; 2, improved; 3, unchanged; 4, deteriorated). Patients not achieving adequate pain relief after 6 weeks were offered a second LDRT course.
Results: To date, 108 patients have been enrolled, resulting in the treatment of 150 joint-sites. Follow-up data were available for 125 sites at 6 weeks, 114 sites at 3 months, and 76 sites at 6 months. The median age of participants was 71.5 years (IQR 10), 72% were female, and mean BMI was 30. Analysis of the 76 sites with 6-month follow-up showed that the most frequently treated sites were hands (n=40, 53%) and knees (n=22, 29%). Mean VAS pain scores were 7.6 at baseline, compared to 3.2, 3.2, and 3.4 at 6 weeks, 3 months, and 6 months, respectively (p<0.0001). The mean difference in VAS from baseline to 6 months was 4.2 (p<0.0001). Median VPS responses were 1 at 6 weeks, and 2 at both 3 and 6 months. Overall, 84% of patients experienced pain improvement, with 64% reporting VAS decreases of = 3 and 41% reporting decreases of = 6. Pain relief was consistent across different joints (knees and hands, p=0.8), genders (p=1.0), and BMI categories (p=0.8). By 6 months, there were 11 instances of Grade 1 dermatitis, 11 sites underwent re-irradiation, and 57% of patients reported reduced or no pain medication usage.
Conclusion: The MOBILE study demonstrates that LDRT for OA can be effectively integrated into modern radiotherapy clinics. Interim results indicate a significant reduction in pain, highlighting the potential of LDRT as a viable treatment option for OA. Further analysis is needed to understand patient characteristics influencing treatment response, which could enhance patient selection and outcomes.