Impact of urinary diversion type on urethral recurrence following radical cystectomy for bladder cancer: propensity score matched and weighted analyses of retrospective cohort

BACKGROUND

The absence of randomized controlled trials and the presence of inherent selection bias in existing studies have led to ongoing uncertainty regarding the impact of urinary diversion (UD) type (orthotopic UD or nonorthotopic UD) on urethral recurrence (UR) following radical cystectomy (RC) for bladder cancer. This study aimed to assess the impact of the UD types on UR after RC and to identify predictive factors associated with UR.

MATERIALS AND METHODS

This retrospective analysis encompassed 612 male patients who underwent RC for urothelial carcinoma of the bladder. Among them, 341 patients received nonorthotopic UD [ileal conduit (IC) or ureterocutaneostomy (UC)], whereas 271 received orthotopic neobladder (NB) between January 2012 and October 2022. To mitigate potential biases, we employed 1:1 propensity score matching (PSM) and stabilized inverse probability treatment weighting (IPTW). Kaplan-Meier analysis and log-rank tests were employed to assess UR-free survival between the IC/UC and NB groups, while multivariable Cox regression analysis was conducted to determine predictive factors for UR.

RESULTS

Among the 612 patients included, 33 (5.4%) experienced UR. PSM yielded matched cohort comprising 412 patients, evenly distributed with 206 patients in each group (IC/UC and NB). Clinicopathological data demonstrated similarity between the two groups. Patients who underwent NB exhibited significantly superior UR-free survival in both PSM (log-rank P =0.033) and IPTW cohorts (log-rank P =0.009). NB reconstruction (vs. IC/UC) emerged as a substantial protective factor against UR [hazard ratio (HR) 0.283; 95% CI: 0.088-0.916; P =0.035], whereas prostatic urethral involvement was identified as a significant risk factor (HR 5.328; 95% CI: 1.298-21.868; P =0.020) in the PSM cohort. Additionally, in the IPTW cohort, NB reconstruction (vs. IC/UC) maintained its significance as a protective factor against UR (HR 0.336; 95% CI: 0.131-0.858; P =0.023) along with neoadjuvant chemotherapy (HR 0.335; 95% CI: 0.116-0.969; P =0.044), whereas prostatic urethral involvement remained a significant risk factor (HR 3.752; 95% CI: 1.484-9.488; P =0.005).

CONCLUSIONS

Even after mitigating selection bias, NB reconstruction holds a protective effect against UR in male patients undergoing RC for bladder cancer.

Do Orthotopic Ileal Diversions Induce Immunological Changes in Retained Urethral Tissue?

Background

A second primary tumors of the urethra (urethral recurrence) after radical cystectomy has been reported to be more infrequent in patients with ileal orthotopic (neobladder) compared to incontinent diversions.

Objective

To investigate whether an altered immunogenic environment of urethral tissue is induced by urethro-ileal anastomosis.

Methods

Between 10/2008 and 12/2009 urethral biopsies of 19 patients (9 neobladder patients, 10 control patients without urethra-ileal anastomosis) were evaluated by conventional histopathological examination and immunohistochemistry for T- (CD3/CD5, CD4, CD8) and B-cell markers (CD20/22, CD79a, CD138). After semi-quantitative assessment, relative cell fractions (B vs. T cells) and subclasses (T4-helper vs. T8-killer cells vs. B cell clones, plasma cells) in neobladder vs. control patients were studied. Unpaired t-test was used for statistical analysis.

Results

Of 19 included patients, 16 were eligible for analysis (7x neobladder, 9x controls). All neobladder patients had undergone cystectomy for UBC. Comparing relative fractions of cells positive for T- and B-cell markers in NB and CO patients, no statistical differences were observed. In 4/7 neobladder patients relative fraction of CD79a positive B-cells was higher than relative fraction of CD3/CD5 positive T-cells (B/T-ratio 1.3). B cells were predominantly CD138 positive plasma cells (5/7 NB patients). Relative B-cell fraction was lower than T-cell fraction in 7/9 control patients (B/T-ratio 0.6). Neither CD 138 positive plasma cells nor CD22 positive B cell clones were predominant. T-helper and CD8 positive T-killer cells were equally distributed in both neobladder (CD4/CD8-ratio: 2.1) and control patients (CD4/CD8-ratio: 1.9).

Conclusions

Comparing neobadder and control patients the distribution of B- and T-cells was statistically not different. However, a trend towards an increased presence of B-cells in urethral tissues of NB patients that could become relevant in a larger study might be suggestive for an immunological response induced by connecting urethral and ileal tissue.