Extracranial palliative radiotherapy for metastatic renal cell carcinoma.

e24156 Background: Radiation therapy (RT) is routinely used for the palliation of metastatic renal cell carcinoma (mRCC) symptoms despite a paucity of literature on RT’s efficacy. Since RCC is considered radioresistant to conventionally fractionated RT, we retrospectively evaluated factors influencing effective symptom palliation with RT for mRCC. Methods: A retrospective review of patients with mRCC between 2011 and 2022 at a high-volume academic radiation center was performed to identify patients with symptomatic extracranial metastatic sites managed with RT. Radiation therapy techniques included three-dimensional conformal RT, intensity-modulated RT, and stereotactic body RT. Symptomatic indications for RT were categorized as pain, neurologic (weakness and numbness), respiratory (hemoptysis and cough), gastrointestinal/genitourinary (GI/GU) bleeding, or multiple. Symptom relief was evaluated from chart reviews at subsequent on-treatment visits or follow-up encounters. Time to symptom alleviation (days) was measured from the RT start date. Descriptive analyses were performed. Results: Of 243 patients included in the study cohort, there were 617 irradiated sites. 560 out of 617 (91.0%) patients were treated for pain, and the other symptoms included neurologic (6.8%), respiratory (3.9%), and GI/GU bleeding (1.5%). The most common RT regimen was 20Gy in 5 fractions (122 lesions; 19.8%) followed by 30Gy in 10 fractions (35 lesions; 5.7%). Symptom relief was observed in 84.9% (95%CI 81.4, 88.1) of patients for pain, 90.8% (95%CI 78.2, 97.6) for neurologic, and 69.9% (95%CI 49.3, 88.0) for respiratory symptoms. The overall proportion of symptom relief was 103/131 (79%) for 20 Gy in 5 fractions versus 27/38 (71%) for 30 Gy in 10 fractions (chi-square P = 0.3). Conclusions: RT is effective for symptom palliation of mRCC. Further studies are required to fully delineate the impact of dose-fractionation and RT modality. [Table: see text]