Stereotactic Ablative Radiotherapy for the Treatment of Upper Urinary Tract Transitional Cell Carcinoma

Purpose: Urothelial carcinomas, also known as transitional cell carcinomas (TCC), account for the majority of upper urinary tract (UUT) tumours. The current gold-standard therapy for operable patients with localized disease is radical nephroureterectomy (RNU). However, some patients are not surgical candidates at the time of diagnosis, and the data on the use of modern radiotherapy for upper urinary tract urothelial carcinomas (UTUC) is scarce. The objective of this study is to present our experience with the treatment of this disease using Stereotactic Ablative Radiotherapy (SABR).
Materials and Methods: This retrospective study included all patients with UTUC treated with SABR at our institution. Normal tissue constraints were set as per Timmerman’s SABR-COMET trial constraints. Charts were reviewed to evaluate for renal function and development of toxicity using the Common Terminology Criteria for Adverse Events version 3.0 (CTCAE v3.0), as well as to assess tumour response on follow-up abdominal scans with computed tomography (CT) or magnetic resonance imaging (MRI) using the Response Evaluation Criteria in Solid Tumours version 1.1 (RECIST 1.1) criteria.
Results: A total of 14 patients, 5 with primary TCC of the ureter and 9 with primary or metastatic TCC of the renal pelvis, were treated with SABR and analyzed retrospectively. Age at the time of treatment ranged from 67 to 95 years-old, with a median of 85 years-old. Most patients received 40 Gy in 8 fractions every second day. Follow-up ranged from 2 to 22 months, with a median of 9 months. Most patients maintained a stable renal function, with only 2 patients transitioning into a higher stage of chronic kidney disease. Acutely, 3 patients developed grade 1 diarrhea, and 1 patient had new grade 1 hematuria. No chronic side effects were observed. Two patients did not have follow-up imaging and were excluded from tumour response analysis. Three patients had complete response of the treated lesion, 5 had partial response, 1 had stable disease and 2 progressed. One patient had complete response of the treated lesion but disease progression with an ipsilateral retroperitoneal lymph node. Another had partial response locally but developed another tumour in the ipsilateral UUT.
Conclusions: This small case series suggests that SABR for UTUC is safe and well-tolerated, with good apparent tumour response to ablative doses of radiotherapy.