2773 - LD-EBRT for Coxarthrosis and GTPS: Correlations between the Season, the Irradiation Area, and the Initial Increase in Pain
Presenter(s)
P. Klepzig1,2, M. Nitsche3, R. Hermann2, Y. Ziert4, C. O. Carl3, R. M. Blach1, J. N. Becker1, and M. A. Sonnhoff1,3; 1Department of Radiotherapy, Hannover Medical School, Hannover, Germany, 2Center for Radiotherapy and Radiooncology Bremen and Westerstede, Westerstede, Germany, 3Center for Radiotherapy and Radiooncology Bremen and Westerstede, Bremen, Germany, 4Institute of Biostatistics, Hannover Medical School, Hannover, Germany
Purpose/Objective(s): Hip disorders are common, with coxarthrosis and greater trochanteric pain syndrome (GTPS) being among the main causes. Seasonal effects on arthritic symptoms are often linked. There are currently no studies of the seasonal efficiency of functional radiotherapy. To investigate whether this influence also affects low-dose external beam radiotherapy (LD-EBRT) efficacy, a retrospective analysis of the overall response rate (ORR) by treatment season was performed.
Materials/Methods: Performing a retrospective evaluation of 262 patients receiving LD-EBRT for coxarthrosis and 549 for GTPS between 2014 and 2024. The planning target volume (PTV) is defined according to the clinical symptomatic. The LD-EBRT was performed with 6 fractions of 0.5 Gy each, for a total dose of 3 Gy. Up to 3 cycles were administered. The patients were examined regarding the season of LD-EBRT and the follow-up. We defined "spring" (March 1 – May 31), "summer" (June 1 – August 31), "autumn" (September 1 – November 30), and "winter" (December 1 – February 28). Also, clinical features were evaluated. Patients who underwent radiation therapy for GTPS but also had coxarthrosis in the planning CT scan were grouped in the “GTPSnCox” group (n = 380) and analyzed. This coxarthrosis was classified based on the Kellgren-Lawrence score.
Results: The ORR of LD-EBRT was 58 % for coxarthrosis and 64 % for GTPS. There was no statistically significant correlation between ORR and the season of LD-EBRT in any of the groups (coxarthrosis: p = 0.261; GTPS: p = 0.33; GTPSnCox: p = 0.068). There was also no correlation between ORR and the seasons of the follow-up (coxarthrosis: p = 0.227; GTPS: p = 0.35; GTPSnCox: p = 0.23). In both entities, there was a highly significant negative correlation between ORR and an initial increase in pain (coxarthrosis: p = 0.009; GTPS: p = 0.00006; GTPSnCox: p = 0.001). Neither the PTV nor the extent of the radiation field influenced the ORR in coxarthrosis (p = 0.593; p = 0.449) or GTPS (p = 0.646; p = 0.195). Radiologically confirmed coxarthrosis did not influence the outcome of LD-EBRT in GTPS (p = 0.693), whereas the presence of a hip prosthesis was correlated with a lower response to therapy (p = 0.03). An age at onset of = 70 years (p = 0.024), a BMI of = 25 kg/m² (p = 0.034) and a higher Kellgren-Lawrence score (p = 0.023) were associated with a poorer treatment response in coxarthrosis. For GTPS, it was shown that LD-EBRT within the first 6 months after symptom onset resulted in a significantly better ORR (p = 0.0001).
Conclusion: LD-EBRT could be an important option for treating inflammatory hip diseases. This effectiveness appears to be independent of the season in which LD-EBRT is administered and the follow-up examination. The PTV and the irradiation field should also be kept as small as possible to protect surrounding structures. An initial increase in pain may indicate a poorer outcome.