[Muscularis mucosae invasion: prognostic factor for intravesical BCG immunotherapy failure for T1 bladder carcinoma]

International audience; OBJECTIVES: To study the prognostic impact of muscularis mucosae (MM) invasion for pT1 bladder cancer treated by transurethral resection (TUR) and adjuvant Bacille Calmette-Guerin (BCG) intravesical immunotherapy. METHODS: Sixty-six patients treated by BCG intravesical instillations were substaged into pT1a and pT1b, regarding Muscularis Mucosae invasion. Tumor grade, associated carcinoma in situ (CIS), multifocality, tumoral size up to 3cm, BCG maintenance were noted. With a mean follow-up of 50.5±38 months, we studied recurrence, progression, overall and specific survival. Cox's model method was used for multivariate analysis. RESULTS: Tumor recurrence was observed in 30±7% and 43±10% (P=0.29) and tumor progression in 16.3±5% and 39±10% (P=0.04) for pT1a and pT1b. The rate of progression was higher (P=0.04) and progression free survival was decreased (P=0.04) for pT1b. Specific death rates were 11±5% and 21±9% (P=0.28), median overall survival was 80.9 [1.5-92] and 48.2 [12-93] months for pT1a and pT1b. Overall and specific survival weren't different between the two populations (P=0.38; P=0.3). Cystectomy rates were 2.3±2% and 30±9% for pT1a and PT1b (P=0.0006). For pT1a patients, recurrence (P=0.8) or progression rates (P=0.64) were no different regarding BCG maintenance immunotherapy but pT1b population had a better progression free survival with BCG maintenance than without (P=0.0051). Only CIS had prognostic value in multivariate analysis. CONCLUSIONS: Tumors with Muscularis Mucosae invasion have a higher risk of progression and BCG failure. Maintenance immunotherapy should be given to improve results with these patients.