Aim: To test the prognostic value of the 1998 WHO/ISUP (World Health Organisation/International Society of Urologic Pathology) consensus classification system in Ta papillary urothelial neoplasms of the bladder. Methods: The histological slides of 322 patients with a primary Ta tumour were classified according to the consensus classification system, and recurrence free survival (RFS) and progression free survival (PFS) were assessed for a mean follow up period of 79 months. In the same patient group, the RFS and PFS rates for the 1973 WHO grading system and a low grade/high grade system were analysed. Results: Recurrent tumours were seen in all categories of the 1998 WHO/ISUP classification system and five year RFS was not significantly different between the groups (p = 0.12). The five year PFS showed a small but significant difference (p = 0.04) between papillary neoplasms of low malignant potential (PNLMP) and high grade papillary urothelial carcinomas (HGPUCs). In the 1973 WHO classification, no significant difference was found in RFS and PFS between the different grades. In the low grade/high grade classification PFS was significantly better for low grade tumours (p = 0.01). Conclusion: The prognostic value of the 1998 WHO/ISUP classification system is limited to predicting PFS, especially between PNLMP and HGPUC. The prognostic value of this system over other grading systems is questionable.

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In a prospective study on the grading of superficial papillary neoplasms of the bladder a distinction was made between tumours showing only increased cellularity without appreciable cellular and nuclear deviation (grade 1), tumours showing slight cellular variation (grade 2a), and tumours showing clear cytological deviation and a tendency to lose normal polarity (grade 2b). Ninety-one patients with a superficial tumour were followed up for a mean of 24 months. Grade 2a tumours recurred later and in fewer patients than grade 2b tumours. Progression was seen in 4% of grade 2a tumours and in 33% of grade 2b carcinomas. Adapting our results to the WHO grading system, we suggest that all tumours in this study defined as grades 1 and 2a should be classified as low grade and tumours defined as grade 2b should be classified as intermediate grade.

Invasion of a carcinoma involves the degradation and penetration of the subepithelial basement membrane (BM). This phenomenon might be used for histopathologic evaluation of neoplasms of the bladder. The authors studied the clinicopathologic data and tissue specimens of 125 cases of urothelial carcinomas collected prospectively. Penetration of the BM was evaluated by immunohistochemical staining of the BM components laminin and type IV collagen. The use of this parameter as a prognostic indicator in bladder cancer was assessed. The 5-year survival rate of patients having tumors with an interrupted or absent BM was significantly lower than that of patients having tumors with an intact BM. The rate of progression was greater in tumors with an interrupted or absent BM than in tumors with an intact BM. No association was found between BM status and recurrence. However, a significant correlation between tumor stage and BM staining was found. A correlation was also found between ploidy and BM staining as well as between histologic grade and BM staining pattern. When evaluating histologic grade, stage, ploidy, age, and BM score as prognostic parameters, the stage of bladder carcinomas turned out to be the most important factor in predicting the survival rate and the progression-free survival. However, BM staining was found to be of value for early identification of microinvasion and is helpful for correct staging of urothelial carcinomas.

A reproducible and discriminating system such as this low-high grade system is an important prognostic factor when stage cannot be established with certainty.