Clinical impact of detrusor muscle in en bloc resection for T1 bladder cancer.

PURPOSE: Detrusor muscle (DM) in the resected specimen of patients with pT1 bladder cancer (BCa) is a quality-of-care criteria. We aimed to assess whether obtaining adequate DM is dependent on surgeon's experience, whether is a surrogate for resection quality, and whether the degree of DM thickness is related to postoperative outcomes in en bloc resection for bladder tumors (ERBT). MATERIALS AND METHODS: We retrospectively analyzed the records of 106 pT1 high-grade BCa patients who underwent ERBT at several institutions. All specimens were reviewed by a single pathologist who assessed the presence or absence of DM and its thickness measured by a micrometer, when present. Early recurrence, defined as pathologically confirmed BCa on repeat resection or tumor recurrence at the first follow-up cystoscopy (within 3 months), was the endpoint reflective of the resection quality. RESULTS: Of 106 patients, DM was detected in 99 (93%), and the median DM thickness was 1.8 mm. Large tumor size (>30 mm) was associated with adequate DM sampling (>1.8mm) (odds ratio [OR]: 6.10, 95% confidence intervals [CIs]: 2.08-17.9, P = 0.001), while surgeon's experience was not. DM presence and DM thickness were both not associated with early recurrence, while positive surgical margin was an independent prognosticator for early recurrence (OR: 3.38, 95% CI: 1.12-10.2, P = 0.031). Excessive DM sampling (>2.1 mm) was associated with prolonged urethral catheterization (OR: 28.8, 95% CI: 3.36-248, P = 0.002). CONCLUSIONS: In ERBT, surgeon's experience seems irrelevant to obtain DM. Resection quality relies on surgical margin status, not the degree of DM. Obtaining excessive DM incurs adverse events/unnecessary medical care.