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

Abstract

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). 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. 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). 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.