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

There is no consensus for grading when more than one grade is present in bladder carcinoma. We propose a grading system that considers the primary (most common) and secondary (second most common) grade of bladder cancer. Grade was correlated with stage of the tumors.

We studied 293 bladder transurethral resections or radical cystectomies. Grade was considered as 1, 2 or 3 according to the 1999 World Health Organization system. The number was repeated when only one grade was seen. A final score was obtained which ranged from 2 to 6. All cases were also graded according to the highest grade area even if it was focal.

According to the highest grade area, the distribution was 80 (74.07%), 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 system 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) between grades 2 + 3 and 3 + 3.

The grading system of combined numbers, stratifies grade 2 into subgroups 1 + 2 and 2 + 2, and grade 3 into subgroups 2 + 3 and 3 + 3 which 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.