Tumor grade heterogeneity in urothelial bladder carcinoma - Proposal of a system using combined numbers

Objective: There is no consensus for grading when more than one grade is pr esent in bladder carcinoma. We propose a grading system that considers the primary (most common) and secondary (second most common) grade of bladder c ancer. Grade was correlated with stage of the tumors. Material and methods: We studied 293 bladder transurethral resections or ra dical cystectomies. Grade was considered as 1, 2 or 3 according to the 1999 World Health Organization system. The number was repeated when only one gr ade was seen. A final score was obtained which ranged from 2 to 6. All case s were also graded according to the highest grade area even if it was focal . Results: According to the highest grade area, the distribution was 80 (74.0 7%), 27 (25.00%) and 1 (0.92%) for grade 1; 31 (24.03%), 69 (53.48%) and 29 (22.48%) for grade 2; and 0 (0%), 17 (30.35%) and 39 (69.64%) for grade 3, corresponding to the stages Ta, T1 and T2-T3, respectively. Using the syst em of combined numbers, grade 2 was stratified into subgroups 1 + 2 and 2 2 which are statistically different (p < 0.05) when considering stage. In grade 3, there was also a trend for statistical difference (p = 0.066) betw een grades 2 + 3 and 3 + 3. Conclusions: The grading system of combined numbers, stratifies grade 2 int o subgroups 1 + 2 and 2 + 2, and grade 3 into subgroups 2 + 3 and 3 + 3 whi ch are statistically different when considering stage. This grading system of combined numbers takes into consideration tumor heterogeneity and may be of value in prospective studies for analysis of prognosis and therapeutic response.