Long-term outcomes in patients with muscle-invasive bladder cancer after selective bladder-preserving combined-modality therapy: a pooled analysis of Radiation Therapy Oncology Group protocols 8802, 8903, 9506, 9706, 9906, and 0233.

ABSTRACT

PURPOSE: Multiple prospective Radiation Therapy Oncology Group (RTOG) protocols have evaluated bladder-preserving combined-modality therapy (CMT) for muscle-invasive bladder cancer (MIBC), reserving cystectomy for salvage treatment. We performed a pooled analysis of long-term outcomes in patients with MIBC enrolled across multiple studies. PATIENTS AND METHODS: Four hundred sixty-eight patients with MIBC were enrolled onto six RTOG bladder-preservation studies, including five phase II studies (RTOG 8802, 9506, 9706, 9906, and 0233) and one phase III study (RTOG 8903). Overall survival (OS) was estimated using the Kaplan-Meier method, and disease-specific survival (DSS), muscle-invasive and non-muscle-invasive local failure (LF), and distant metastasis (DM) were estimated by the cumulative incidence method. RESULTS: The median age of patients was 66 years (range, 34 to 93 years), and clinical T stage was T2 in 61%, T3 in 35%, and T4a in 4% of patients. Complete response to CMT was documented in 69% of patients. With a median follow-up of 4.3 years among all patients and 7.8 years among survivors (n = 205), the 5- and 10-year OS rates were 57% and 36%, respectively, and the 5- and 10-year DSS rates were 71% and 65%, respectively. The 5- and 10-year estimates of muscle-invasive LF, non-muscle-invasive LF, and DM were 13% and 14%, 31% and 36%, and 31% and 35%, respectively. CONCLUSION: This pooled analysis of multicenter, prospective RTOG bladder-preserving CMT protocols demonstrates long-term DSS comparable to modern immediate cystectomy studies, for patients with similarly staged MIBC. Given the low incidence of late recurrences with long-term follow-up, CMT can be considered as an alternative to radical cystectomy, especially in elderly patients not well suited for surgery.