Is The Cancer Genome Atlas (TCGA) bladder cancer cohort representative of invasive bladder cancer?

PURPOSE: The Cancer Genome Atlas (TCGA) Research Consortium has conducted a comprehensive molecular characterization of invasive bladder cancer (BCa). This open-access dataset has become the critical reference for studying biomarkers and mechanisms of disease in BCa. In order for this data to be considered representative, and to allow comparisons of markers between cohorts, clinicopathologic characteristics of this cohort need to conform to those established for this disease state. The aim of this study was to critically evaluate clinicopathologic characteristics and outcomes of the TCGA BCa cohort in comparison with published cystectomy series.

METHODS: Clinicopathologic parameters from the provisional TCGA BCa cohort were accessed. Descriptive statistics were performed in the background of widely cited cystectomy series.

RESULTS: The TCGA BCa cohort included a higher rate of patients with non-organ-confined disease (62%) and lymph node involvement (30%) compared to previous series. The 5-year overall survival was slightly lower when compared to standard cystectomy series (43%), but it was consistent with prior reports when stratified by tumor stage (69%, 48%, and 23% for pT≤2 pN0, pT>2 pN0, and any pT pN+tumors, respectively). Importantly, established risk factors (pT>2 and pN+) were confirmed as independent predictors of poor overall survival.

CONCLUSIONS: The characteristics of the TCGA BCa cohort include a high proportion of advanced tumors, but outcomes in major subgroups show concordance with previous series. Therefore, molecular data from this cohort can be considered representative of invasive BCa and serve as a valuable resource to validate prognostic biomarkers.