Abstract
PurposePaucity of reliable long-term data on the prognostic implications of the 2004 WHO bladder cancer classification system necessitates utilisation of both this and the 1973 grading systems. This study evaluated, in noninvasive (pTa) bladder tumours, the prognostic value of the 2004 system independently and in combination with the 1973 system while establishing concordance between tertiary centre uropathologists.MethodsWe used a cohort of non-muscle invasive bladder cancer (NMIBC) patients diagnosed between 1991 and 93 where tumour features were gathered prospectively with detailed cystoscopic follow-up data recorded over 15 years. Initial grading was by one senior expert uropathologist (UP1) using the 1973 WHO classification alone. Subsequently, two other expert uropathologists (UP2 and UP3), blinded to the previous grading, re-evaluated the pathology slides and graded the tumours using both the 1973 and 2004 systems. Association between grade and recurrence/progression was analysed and the Cohen Kappa test assessed concordance between pathologists.ResultsOf 370 new NMIBC, 229 were staged noninvasive (pTa). Recurrence rates were 46.2% and 50.0% for LGPUC (low-grade papillary urothelial carcinoma) and HGPUC (high-grade papillary urothelial carcinoma), respectively, while progression was seen in 3.9% and 10.0% of LGPUC and HGPUC, respectively. Concordance between uropathologists UP2 and UP3 for the 2004 and 1973 systems was good (Kappa = 0.69) and fair (Kappa = 0.25), respectively.ConclusionsWith 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.
Highlights
The management of patients with bladder cancer, in the absence of reliable biomedical markers, is dependant largely on the Histopathological interpretation of cellular appearance
In non-muscle invasive bladder cancer (NMIBC), which accounts for up to 80% of new bladder cancers, the risk of recurrence can be as high as 80% and the risk of progression
Due to the apparent lack of reproducibility and accuracy of the 1973 classification system in part due to poor description of criteria for each grade [6], a new grading system was suggested 25 years later [7]—as this grading system was published in the 2004 edition of the “blue books” WHO classification of tumours, it became popularised as the 2004 classification of urothelial carcinoma grading [8]
Summary
The management of patients with bladder cancer, in the absence of reliable biomedical markers, is dependant largely on the Histopathological interpretation of cellular appearance. To this end, the WHO introduced the 1973 classification system [1]. The WHO introduced the 1973 classification system [1] To date, this forms the foundation of many clinical trials, nomograms, and risk calculators [2–4]. In non-muscle invasive bladder cancer (NMIBC), which accounts for up to 80% of new bladder cancers, the risk of recurrence can be as high as 80% and the risk of progression. World Journal of Urology (2021) 39:425–431 to muscle invasive cancer can be up to 20%. Due to the apparent lack of reproducibility and accuracy of the 1973 classification system in part due to poor description of criteria for each grade [6], a new grading system was suggested 25 years later [7]—as this grading system was published in the 2004 edition of the “blue books” WHO classification of tumours, it became popularised as the 2004 classification of urothelial carcinoma grading [8]
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