Commentary on: "Comprehensive transcriptional analysis of early-stage urothelial carcinoma." Hedegaard J, Lamy P, Nordentoft I, Algaba F, Høyer S, Ulhøi BP, Vang S, Reinert T, Hermann GG, Mogensen K, Thomsen MB, Nielsen MM, Marquez M, Segersten U, Aine M, Höglund M, Birkenkamp-Demtröder K, Fristrup N, Borre M, Hartmann A, Stöhr R, Wach S, Keck B, Seitz AK, Nawroth R, Maurer T, Tulic C, Simic T, Junker K, Horstmann M, Harving N, Petersen AC, Calle ML, Steyerberg EW, Beukers W, van Kessel KE, Jensen JB, Pedersen JS, Malmström PU, Malats N, Real FX, Zwarthoff EC, Ørntoft TF, Dyrskjøt L. Cancer Cell. 2016 Jul 11;30(1):27-42.

Non-muscle-invasive bladder cancer (NMIBC) is a heterogeneous disease with widely different outcomes. We performed a comprehensive transcriptional analysis of 460 early-stage urothelial carcinomas and showed that NMIBC can be subgrouped into 3 major classes with basal- and luminal-like characteristics and different clinical outcomes. Large differences in biological processes such as the cell cycle, epithelial-mesenchymal transition, and differentiation were observed. Analysis of transcript variants revealed frequent mutations in genes encoding proteins involved in chromatin organization and cytoskeletal functions. Furthermore, mutations in well-known cancer driver genes (e.g., TP53 and ERBB2) were primarily found in high-risk tumors, together with APOBEC-related mutational signatures. The identification of subclasses in NMIBC may offer better prognostication and treatment selection based on subclass assignment.