Impact of chemoradiotherapy for bladder cancer on pre-existing hydronephrosis and development of new hydronephrosis

Radical cystectomy is the recommended treatment in muscle-invasive bladder cancer patients with hydronephrosis. However, there is no literature on the impact of chemoradiotherapy on pre-existing hydronephrosis or the development of new hydronephrosis. This study aims to assess the incidence, aetiology, and management of hydronephrosis before and after chemoradiotherapy (CRT).

Retrospective cohort study, including patients with muscle-invasive bladder cancer (MIBC) treated with CRT between 1 January 2014 and 5 December 2022. Patients with urethral urothelial carcinoma and with stage T1 were included if they received total bladder irradiation. Exclusion criteria were renal transplantation, ureteral reimplantation, sequential chemotherapy and radiotherapy, CRT as preoperative treatment, urinary diversion before CRT, transitioning to palliative radiotherapy, and sarcomatoid or signet ring cell carcinoma type. Patients were also excluded if no follow-up data was available. In this period 181 patients received CRT, after applying the exclusion criteria a total of 146 patients were eligible for evaluation. The main outcome was hydronephrosis, defined as any grade of dilatation of the renal pelvis with or without ureter dilatation, identified on any form of imaging.

146 patients were included, 27 with pre-existing hydronephrosis before CRT and 119 without. The mean age of the patients was 73 years (Standard deviation (SD): 8.59) and 74% was male. Hydronephrosis in patients with pre-existing hydronephrosis persisted after CRT in 74% (n = 20), with 44% (n = 12) receiving drainage. Of the patients without pre-existing hydronephrosis, 21% (n = 25) developed hydronephrosis, and 52% (n = 13) of the patients that developed hydronephrosis required drainage. Tumour was responsible for pre-existing hydronephrosis in 93% (n = 25) and for hydronephrosis after CRT in 22% (n = 6) with pre-existing hydronephrosis. In patients without pre-existing hydronephrosis, hydronephrosis was caused by a tumour in 11 out of 25 patients.

Pre-existing hydronephrosis persists after CRT for MIBC in ~ 75% of patients and ~ 20% of patients without pre-existing hydronephrosis develops hydronephrosis after CRT. Around half of these patients receive drainage. These findings may assist in counselling patients with pre-existing hydronephrosis regarding the potential outcomes following CRT.