Clinical significance of interobserver differences in the staging and grading of superficial bladder cancer

Objective To assess the reliability of the histological diagnosis of bladde r cancer by assessing the interobserver variability of staging and grading in pTa/pT1 tumours and evaluating the clinical significance of discrepancie s. Materials and methods All sections from 301 superficial bladder carcinomas were reviewed by one pathologist. The prognostic relevance of grade and sta ge from both the initial and review diagnosis were determined in 128 patien ts for whom there was long-term follow-up information. Results There were significant interobserver differences in both the gradin g and staging of tumours. From a total of 235 tumours that were initially c onsidered pT1, the reviewer classified 35% as pTa, 56% as pT1, 6% as pT1- ( at least pT1), and 3% as pT2-4. In 39% of all biopsies there were interobse rver differences in tumour grade. The prognostic significance of grade and stage differed between the initial pathology report. and the reviewer's dia gnosis. The reviewer's staging allowed a better estimate of the risk of sub sequent tumour progression than the initial staging. Progression was signif icantly more common in 49 tumours in which the reviewer agreed with stage p T1 than in 29 tumours that were down-staged from pT1 to pTa (P = 0.0116). H owever, the initial tumour grade (P = 0.0386) but not the reviewer's grade (P = 0.2645) was significantly linked to progression. Conclusions These results show that grading and staging by different pathol ogists have varying prognostic implications. If possible, biopsies from bla dder tumours should be independently evaluated by two different pathologist s before radical therapy is administered.