ANALYSIS OF GROWTH FRACTIONS OF RENAL CELL CARCINOMA BY THE MONOCLONAL ANTIBODY Ki-67

The monoclonal antibody Ki-67 recognizes a human nuclear antigen that is present in proliferating cells (G1, S, G2 and M cycling stages of cell division) exclusively, but is absent in GO cycling stage. We performed immunohistochemical analysis of renal cell carcinomas using Ki-67 antibody, and investigated the relationship between the proportion of Ki-67 positive cells and pathological findings of renal cell carcinomas.The tissues were obtained from 36 patients with renal cell carcinoma who underwent radical nephrectomy. Cryostatfrozen sections were cut at 5μm and stained with avidin-biotin-peroxidase complex method. The percentage of Ki-67 positive cancer cells to the total amount of cancer cells was expressed as growth fraction (GF). We obtained the following results with regard to the relationship between GF and pathological findings of renal cell carcinomas.1) GFs in pathological grades were 6.58±4.57% (mean±SD) for grade 2 (n=13) and 1.20±0.70% for grade 1 (n=21). GF in grade 2 was significantly higher than that in grade 1(p<0.01). GF for Grade 3 (n=2) were 9.2% and 27.8% respectively.2) GFs in the pathological stages were 8.12±7.64% for pT3 (n=13) and 1.84±1.30% for pT2 (n=23). GF in pT3 was significantly higher than that in pT2 (p<0.01).3) GFs in the cancers with and without lymph node involvement were 13.84±8.48% (n=5) and 2.80±2.74% (n=27), respectively. GF in the cancers with lymph node involvement was significantly higher than that without lymph node involvement (p<0.01).GF, which was determined by immunohistochemical analysis using Ki-67 antibody, apparently correlated with pathological grade, stage, and lymph node involvement. These findings suggest that GF in the renal cell carcinoma indicates a growth potential of each cancer and is useful for estimating malignancy of the renal cell carcinoma.