Urologists frequently encounter malignant ureteral obstruction (MUO) caused by advanced urological or non-urological malignant disease, but the treatment policy is unclear. The present study examined the risk factors for predicting ureteral stent failure in patients with MUO after ureteral stent insertion and the change in the renal function after retrograde ureteral stent insertion in cases of bilateral hydronephrosis.
A total of 39 patients who required ureteral stent placement for MUO at Yokohama City University Medical Center (Yokohama, Japan) between February 2007 and May 2016 were included in this study. The age, gender, type of cancer, hydronephrosis side, pre-stenting estimated glomerular filtration rate (eGFR), and eGFR increase were assessed as predictive factors for stent failure. Among these 39 patients, 25 showed bilateral hydronephrosis. Thirteen of these patients had bilateral ureteral stents placed, and the remaining 12 had a unilateral ureteral stent placed. The renal function and overall survival (OS) were analyzed between these two groups.
Among all 39 patients, 9 (23.1%) had stent failure. A univariate analysis revealed that causative disease (gastrointestinal cancer vs. others; p = 0.045) and laterality of hydronephrosis (bilateral vs. unilateral; p = 0.05) were associated with stent failure. A multivariate analysis revealed that only age (hazard ratio, 0.938; 95% confidence interval, 0.883–0.996; p = 0.038) was associated with stent failure. A Kaplan-Meier analysis and log-rank test indicated that having a unilateral ureteral stent placed was not correlated with a lower OS rate than having bilateral ureteral stents placed (p = 0.563). Among patients with bilateral hydronephrosis, the increase in the eGFR of those who had bilateral ureteral stents placed was not significantly different from that of those who had a unilateral ureteral stent placed (p = 0.152).
We revealed that age > 60 years was helpful for predicting stent failure. MUO due to gastrointestinal cancer and bilateral hydronephrosis may be predictive of stent failure. These factors may help urologists decide the optimal time to perform early percutaneous nephrostomy. These findings suggest that patients with bilateral hydronephrosis do not necessarily need to have a ureteral stent placed into both sides of the hydronephrosis.