Grading of human urothelial carcinoma based on nuclear atypia and mitotic frequency. II. Prognostic importance

A grading system was applied in a retrospective study of 124 patients with transitional cell carcinoma of the bladder using a modified Bergkvist system. The intermediate World Health Organization (WHO) grade II tumors were divided into supposedly benign and malignant forms of grades IIa and IIb, respectively. The 5-year survival was 92% for patients with grade IIa urothelial carcinoma, compared to 43% for patients with grade IIb tumors. The corresponding figures for grades I and III tumors were 100 and 44%, respectively. When excluding carcinoma in situ (5-year survival 50%) no patient with a noninvasive tumor (stage Ta) died of bladder carcinoma within 5 years, compared to 50% of those with invasive cancers (stages T1 to T4). We propose a new grading system in which grades I and IIa are embraced as grade A, grades IIb and III as grade B, and grade IV as grade C. The 5-year survival rate in the 3 grades was 94, 44 and 27%, respectively. Grade A seems to represent a type of tumor with universally favorable prognosis, in contrast to grades B and C. This offers practical advantages, since the former can be treated conservatively, whereas the latter need more urgent radical intervention, especially in patients in whom invasive growth is recorded.