Ureter Tolerance in Patients Treated with Stereotactic Body Radiation Therapy on Abdominopelvic Lymph Nodes: Analysis on Dose-related Late Toxicity.
retrospective_cohort · Level III
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- Also identified by DOI 10.1016/j.ijrobp.2025.05.087.
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Abstract
This study evaluated late ureteral toxicity in relation to dose in patients treated with stereotactic body radiation therapy (SBRT) on abdominopelvic lymph node (A-P LN) oligometastases and assessed differences between planned and received ureteral dose. Patients treated between 2011 and 2023 with SBRT on A-P LN oligometastases from various primary tumors were retrospectively reviewed. Toxicity was graded using the Common Terminology Criteria for Adverse Events version 5.0. Dose-volume histogram parameters (maximum dose to the ureter [D<sub>max</sub>] maximum dose to 0.1 cc of the ureter [D<sub>0.1cc</sub>], and maximum dose to 0.5 cc of the ureter [D<sub>0.5cc</sub>]) from ureters receiving >10 Gy were extracted and compared with published ureteral constraints (D<sub>max</sub> 108, D<sub>0.1cc</sub> 108, and D<sub>0.1cc</sub> 77 Gy equivalent dose of 2 Gy per fraction with a:b ratio of 3 Gy [EQD2<sub>3</sub>]). Interfraction dose variation was derived from patients who were treated with online adaptive SBRT. The study included 144 patients, of whom 121 had a total of 137 ureters that were treated with <10 Gy. Most patients (85%) received 45 Gy in 5 fractions. The median ureter D<sub>max</sub> and D<sub>0.1cc</sub> were 60 and 42 Gy EQD2<sub>3</sub>, respectively. No grade (G) ≥ 4 toxicities were observed. Three patients (2%) developed G3 ureteral obstruction, with D<sub>max</sub> values of 121, 97, and 74 Gy EQD2<sub>3</sub>. Five patients (4%) experienced any G of late urinary toxicity, but only 1 of them exceeded the D<sub>max</sub> of 108 Gy EQD2<sub>3</sub>. In total, 31 (23%) patients did not experience late toxicity, despite exceeding this parameter. No significant difference was found between the planned and received ureter dose (D<sub>0.1cc</sub> 25 vs 22 Gy EQD2<sub>3,</sub>P = .23). The median follow-up was 28 months. The incidence of G3 ureteral toxicity after SBRT on A-P LN oligometastases is low (2%). Published dose constraints were violated in 23% of the patients without reported toxicity, suggesting other factors may contribute. Furthermore, no difference was found between the planned and received ureter dose, indicating that the planned dose is a reliable estimate of the dose received.