Reproducibility and prognostic value of WHO1973 and WHO2004 grading systems in TaT1 urothelial carcinoma of the urinary bladder.

Background European treatment guidelines of TaT1 urinary bladder urothelial carcinomas depend highly on stage and WHO1973-grade but grading reproducibility is wanting. The newer WHO2004 grading system is still debated and both systems are currently used.