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 progression-free 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.