Ureteral obstruction leading to hydronephrosis may be present in up to one-half of patients with bladder cancer. Preoperative drainage of the hydronephrotic kidney is often pursued to relieve symptoms or maximize renal function. Effective drainage can be achieved in many cases by either ureteral stenting or placement of a percutaneous nephrostomy tube.
The potential for urothelial carcinoma to seed other parts of the urothelium is debated. There have been historical concerns and provocative studies suggesting that the placement of a ureteral stent in patients with bladder cancer may increase the risk of developing upper tract urothelial carcinoma (UTUC) — the work Dr. Bernhard Kiss and colleagues published in The Journal of Urology in 2017 provided such evidence. Authors have theorized that the stent provides an avenue for reflux of urine and urothelial carcinoma cells into the upper tract.
Furthermore, any time the ureter is manipulated, a theoretical risk of urothelial injury occurs and therefore a potential risk of stricture or other complications exists.
Evaluating the risk of UTUC in patients with bladder cancer receiving cystectomy
Recently, R. Jeffrey Karnes, M.D., Urology, Mayo Clinic in Rochester, Minnesota, and Urology colleagues sought to evaluate the implications of preoperative hydronephrosis drainage strategies. Their work was published online in Urology in 2020 and was also awarded best poster at the American Urologic Association’s 2020 National Meeting.
The authors of the study identified 1,049 patients who underwent cystectomy for bladder cancer at Mayo Clinic between 2000 and 2015. The patients were divided into four groups based on their preoperative status relative to hydronephrosis:
- No hydronephrosis (75%, N = 787)
- Hydronephrosis with no preoperative drainage (13%, N = 132)
- Hydronephrosis addressed by nephrostomy tube (3%, N = 36)
- Hydronephrosis drained by ureteral stent (9%, N = 94)
UTUC rates were assessed by Kaplan-Meier analyses. Five years after cystectomy, there was no significant difference in rates of UTUC with 6.6%, 10.2%, 17.0% and 18.7% of patients in groups 1 through 4 having UTUC diagnosed, respectively (p = 0.13).
On multivariable analysis, both nephrostomy tube drainage (HR 4.10, p = 0.02) and ureteral stenting (HR 2.35, p = 0.04) were associated with increased risk of UTUC compared with patients without hydronephrosis. However, there was no significant difference in UTUC development between patients treated with either a nephrostomy tube or a ureteral stent (p = 0.43). This relationship persisted when a subset of patients with cancer clinical stage II or higher was assessed (p = 0.54).
Interestingly, the degree of hydronephrosis was associated with future UTUC diagnosis: Severe hydronephrosis was associated with a four times greater risk of UTUC (p = 0.02). Furthermore, hydronephrosis severity was associated with increased risk of overall and cancer-specific mortality.
Ureteral stricture after cystectomy
Ureteral stricture developed in 8.5%, 9.2%, 8.3% and 10.6% of patients in groups 1 through 4 respectively, and there was not a statistical difference between these rates (p = 0.918).
Also, the risk of pyelonephritis after cystectomy was not affected by preoperative hydronephrosis nor the type of drainage in the setting of hydronephrosis (p = 0.778).
Implications for patients
“These data were enlightening for us, especially in the context of previous debate regarding this issue,” says Vidit Sharma, M.D., a Mayo Clinic scholar with Urology at Mayo Clinic’s campus in Rochester, Minnesota. “Our results do not corroborate the results of some previous studies, which did suggest that nephrostomy tube placement may be associated with a lower risk of developing UTUC than stent placement. However, our data suggest that hydronephrosis before cystectomy can be treated, if needed, by the means most acceptable to the patient and urologist, and that the type of drainage chosen for hydronephrosis should not be associated with cancer recurrence or complications.”
Dr. Karnes further summarizes the study: “Based on our large cohort of patients receiving radical cystectomy and a robust statistical analysis, we can say that there does not appear to be an increased risk of UTUC in patients receiving preoperative ureteral stenting for hydronephrosis prior to cystectomy, relative to placement of a nephrostomy tube. This confirmation certainly helps us inform and reassure many of our patients who may require treatment of hydronephrosis before receiving definitive therapy with cystectomy.”