134 - Safety and Efficacy of Stereotactic Body Radiotherapy (SBRT) for Localized Renal Pelvic and Ureteral Carcinoma

05:20pm - 05:30pm ET

Room 205

Presenter(s)

Xiaoying Li, MD - Peking University First Hospital, Beijing, Beijing

X. Li¹, X. Li², X. S. Gao¹, Q. Tang², G. Xiong², Y. Huang², and M. W. Ma¹; ¹Department of Radiation Oncology, Peking University First Hospital, Beijing, China, ²Peking University First Hospital urology department, Peking, China

Purpose/Objective(s): Radiotherapy plays a very important role in the organ-preserving treatment of bladder cancer.The application of radical SBRT in UTUC have not been well assessed. This study aims to analyze the efficacy and safety of stereotactic body radiation therapy (SBRT) as a kidney-sparing treatment approach for patients with UTUC.

Materials/Methods: This is a phase 2 single-arm nonrandomized clinical trial evaluating SBRT as only treatment in patients with high-risk UTUC from March 2023 to August 2025. Patients with metastatic, recurrent, or locally advanced disease were excluded. Pathological diagnosis was conducted via urinary cytology or tissue biopsy.

The SBRT prescription dose was 50 Gy delivered in 10 fractions over two weeks,or 30-40Gy delivered in 5 fractions over one week.The imaging evaluation at 1 month after radiotherapy was conducted in accordance with the RECIST criteria. The primary end point was the overall response rate (ORR). The secondary end point was kidney function.Based on a single-arm binomial design, a sample size of 33 patients achieves 90% power to detect an ORR of 90% against a historical control of 70% using a one-sided binomial test at a=0.05. Assuming a 10% dropout rate, a total of 37 patients will be enrolled.

Results: 38 patients were finally included in the analyses,the median age is 79(43-94). Complete response (CR)was achieved in 20 patients (60.5%), parcial response (PR) was observed in 12 patients (31.6%). The ORR was 92.1% (35/38), reflecting a high degree of treatment success.Significant increase in the level of creatinine was noted at 6 months compared to values after SBRT (104.3 µmol/L Vs 119.3 µmol/L,P=0.006). The mean decrease in estimated glomerular ?ltration(eGFR) rate was –7.6 ml/min/1.73 m² after 6 months(P=0.013).13 patients (46.4%) suffered renal function impairment, and renal function benefit was observed in 2 patients (5.3%). Two patients (5.3%) developed hydronephrosis and they were both successfully managed with indwelling double-J stents after 6 months. At 1 year, the rates for lymph node metastasis-free survival (LNMFS), metastasis-free survival (MFS), LRFS and BRFS were 88.4%, 93.9%, 88.4% (95% CI: 78.3%-99.9%) and 85%, respectively.

Conclusion: SBRT demonstrated promising ef?cacy and manageable safety in selected patients with localized high-risk UTUC,with acceptable rates of renal function impairment and ureteral injury.

Abstract 134 – Table 1

Variables	eGFR (ml/min/1.73 m²)	Creatinine (µmol/L)
Baseline	53.1 (40.5-65.8)	104.3 (83.8-146)
After SBRT	53.6 (33.6-70)	101.6 (81-140)
After 1 month	50.7 (38.1-65)	106.3 (90-127)
After 6 months	45.5 (27.2-59)	119.3 (84-181)
Comparison^a
Baseline vs. After SBRT	1.000	1.000
Baseline vs. After 6 months	0.013	0.060
After 1 month vs. After 6 months	0.020	0.007