Proliferative activity in human urologic malignancies: a preliminary study

Cellular proliferative activity was evaluated by the determination of 3H-thymidine labeling index (LI) in 20 specimens of human urologic malignancies (13 renal cell carcinomas and 7 transitional cell bladder carcinomas). Very low LI values were found in renal cell carcinomas, with a median value of 0.28%. Slightly higher proliferative activities were observed in bladder carcinomas, with a median LI value of 1.96%. No significant correlations were found between proliferative activity and pathologic stage or histologic grading in renal cell carcinomas. Although the number of bladder carcinomas evaluated does not allow any definite conclusion, an increase in LI values was found from in situ to invasive carcinoma and from tumors at stage I to tumors at stage III.