Combining two grading systems: the clinical validity and inter-observer variability of the 1973 and 2004 WHO bladder cancer classification systems assessed in a UK cohort with 15 years of prospective follow-up

Abstract

With good inter-observer concordance, the 2004 WHO classification system of noninvasive bladder tumours appears to accurately predict recurrence and progression risks. The combination of both grading systems to low-grade tumours allows further refinement of the natural history.