A simplified grading method of transitional cell carcinoma of the urinary bladder : reproducibility, clinical significance, and prognostic comparison with other parameters

Objective To determine the extent to which the biological potential of transitional cell neoplasms can be predicted by histological grading of the primary tumour in a two grade system using simple histological criteria and to evaluate the additional value of grading when combined with other prognostic factors. The inter-observer variability of the World Health Organization grading and the two grade system was tested. Patients and methods The study included 311 patients with newly diagnosed transitional cell carcinoma of the urinary bladder. Two-hundred and fifty-six patients (82.3%) were men and 55 (17.7%) were women. Age ranged from 17 to 92 years with a mean of 66 years. The median follow-up was 38 months, with a maximum of 150 months (mean 46.2 months). Results A simplified grading system was developed in which only low-grade and high-grade tumours were distinguished. Reproducibility of this grading system was good to excellent with a group kappa value of 0.78. The survival of patients with low-grade tumours was significantly better than that of patients with high-grade tumours (P <0.0001). The progressionfree interval was also significantly longer in patients with low-grade tumours than in patients with high-grade tumours (P= 0.0032). Combining low-high grading, histological stage, mitotic index and age, histological stage appeared to be the most important parameter in predicting survival and progression. Conclusion A reproducible and discriminating system such as this low-high grade system is an important prognostic factor when stage cannot be established with certainty.