[T1 bladder carcinoma: prognostic value of the muscularis mucosae invasion (T1a/T1b). A multicenter study by the French Urological Association (CCAFU)].

Objective: The aim of this multicenter study was to determine the prognostic value of the depth of invasion of lamina propria and more specifically the influence of the invasion of the muscularis mucosae on survival parameters in T1 bladder carcinoma.

Patients: Six urological centers included patients between 1994 and 2004 who had an initial T1 bladder tumor. All T1 tumors were substaged according to the muscularis mucosae (MM) invasion into T1a (no invasion beyond the MM) and T1b (invasion beyond MM but preserving the muscle). Among the 387 patients included, 269 (69.5%) were found T1a and 118 (30.5%) T1b. Mean follow-up was 45.4 months. T1a and T1b groups were comparable except for tumor grade that was higher in T1b (p<0.001).

Results: Survival without recurrence was not significantly different between T1a and T1b groups (p<0.3) but T1a stage was found as an independent factor for survival without progression (RR=0.49; IC 95%=[0.71-0.90]), specific survival (RR=0.33; IC 95%=[0.16-0.67]) and global survival (RR=0.52; IC 95%=[0.32-0.85]).

Conclusion: This study, the largest on the subject to our knowledge, have shown that muscularis mucosae invasion was a prognostic factor for survival without progression, specific survival, and global survival. We support that routine pathological assessment of the level of MM invasion in patients with stage T1 bladder cancer should be included in the histopathological report.