Adjuvant single-dose upper urinary tract instillation of mitomycin C after therapeutic ureteroscopy for upper tract urothelial carcinoma: a single-centre prospective non-randomized trial

Purpose To address the safety and feasibility of upper urinary tract instillation of a single dose of mitomycin (ASDM) immediately after therapeutic ureteroscopy for upper tract urothelial carcinoma (UTUC) and to compare urothelial (ipsilateral or bladder) recurrence rates in the ASDM group and controls. Materials and Methods Between April 2015 and August 2018, 52 patients affected by UTUC were treated by endoscopic ablation, of whom 26 were selected for ASDM. Clinical and perioperative data and 30-day complications were recorded. The primary endpoint was urothelial recurrence-free survival (URFS) evaluated by second-look ureteroscopy and CT scan/ureteroscopy every 6 months. Results ASDM was administered via a single-J (19/25, 76%) or a double-J (6/25, 24%) in 25/26 (96%) patients. Median follow-up was 18 months (IQR 10-29). The urothelial recurrence rate was 23.5% and 55.5% in the ASDM group and controls, respectively (p=0.086). Mean URFS was 28.8 months in the ASDM group vs 18.8 months in controls (log-rank p=0.067). On multivariate Cox regression, ASDM was associated with a 7.7-fold lower risk of urothelial recurrence (HR=0.13; 95% CI 0.03-0.65; p=0.01). Clavien grade ≤II complications occurred in 32% (8/25) and 30.7% (8/26) of the ASDM and control group, respectively (p=0.9). Two Clavien III complications occurred in the ASDM group: bladder haematuria after concomitant TURB and obstructive kidney failure in a single-kidney patient. Conclusions ASDM was well tolerated after therapeutic ureteroscopy. It appears to reduce the risk of urothelial recurrence in patients affected by low-grade UTUC without bladder tumour. Therefore, its use should be evaluated.