Abstract Code: IUC24396-89

The fate of the hydronephrotic kidney in muscle-invasive bladder cancer.

M. Gami 1, T. Rich 1, H. Motiwala 1

(1) Southend University Hospital, Essex, UK. – United Kingdom

Background: Hydronephrosis is an independent predictor of poor clinical outcomes in muscle-invasive bladder cancer (MIBC), associated with higher rates of extravesical disease and reduced survival. However, its impact on renal function remains unclear. This study evaluates changes in serum creatinine over two years and assesses whether de-obstruction at diagnosis influences renal function.

Methods: We conducted a retrospective analysis of patients diagnosed with MIBC and hydronephrosis (2020-2024). Inclusion criteria were ≥T2 disease and serum creatinine measurements at diagnosis and two years post-diagnosis. Patients without oncologic intervention, those who died within one year, or decompression after initial treatment were excluded. Data were extracted from hospital records.

Results: Among 52 patients (mean age 68.5, 30 males), most had T2/T3 disease; 19 had nodal involvement (N+), and 11 had metastases (M+). Treatment included cystectomy (n=25), chemoradiotherapy (n=23), radiotherapy (n=10), and chemotherapy alone (n=4). Creatinine increased by a mean of 15 µmol/L (p=0.0325) at one year in all treatment groups, but there was no significant difference at 2 years. In cystectomy patients, creatinine increased significantly at one year (13 µmol/L, p=0.04) but not at two years. This was primarily driven by patients who were de-obstructed before cystectomy (Cr +29.80 µmol/L, p=0.01). Non-surgical treatments showed no impact on renal function. Most de-obstruction was pre-chemoradiotherapy.

Conclusions: Patient selection for de-obstruction is critical, particularly in those receiving chemotherapy, as there is evidence that renal function can be preserved. Our findings suggest de-obstruction can be avoided when cystectomy is planned, as it may help preserve renal function at 1 year.