Impact on oncological outcomes of detrusor muscle absence in pTaHG urothelial carcinoma of the bladder? The end of the "jump" of the lamina propria layer myth.

Purpose: To evaluate the impact of detrusor muscle (DM) absence on oncological outcomes in patients with pTaHG within a large, multicenter cohort.

Methods: This is a retrospective multicenter study based on a national database including 12 international expert centers. All patients who underwent transurethral resection of bladder tumor (TURBT) for a new diagnosis of pTaHG bladder cancer between January 2010 and December 2018 were included and divided into two groups according to the presence or absence of DM. Kaplan-Meier curves were used to illustrate survival outcomes, while Cox regression analyses were conducted to identify independent predictors of survival.

Results: Overall, 418 patients had either pTaHG with DM (n = 365;87.3%) or without DM (n = 53;12.7%). After a median follow-up of 30 months, IQR [15;55], the 5-year RFS (40% vs. 50%; p = 0.2) and the 5-year PFS (75% vs. 86%; p = 0.2) were similar between both groups. Cox-regression analysis confirmed that absence of DM was not significantly associated with RFS (HR = 0.68; 95%CI= [0.41-1.15]; p = 0.15) and PFS (HR = 0.68; 95%CI= [0.27-1.69]; p = 0.40). Among 53 patients without DM, 29 (54.7%) underwent a second-look TURBT, with no impact on 5-year RFS (p = 0.1) and 5-year PFS (p = 0.07). Additionally, Cox-regression analysis confirmed that the absence of second-look was not associated with RFS (HR = 0.28; 95%CI= [0.09-0.93]; p = 0.04) and PFS (HR = 0.05; 95%CI= [0.00-0.89]; p = 0.04).

Conclusion: Absence of DM on pathological specimen of pTaHG tumors had no impact on disease recurrence or progression occurrence, calling into question the need for routine second-look procedures for these patients.