[Correlation of intratumor DNA ploidy distribution pattern and Ki-67 index in large bowel carcinomas]

Seventy cases of surgically resected specimens of large-bowel carcinomas were used. DNA ploidy was determined by flow cytometry for step-wise sections in each carcinoma. Intratumor DNA ploidy distribution pattern was classified into 5 types: Type A showing diploidy in all sections; Type B showing aneuploidy in all sections with the same DNA index (DI); Type C showing diploidy in the majority of the sections and aneuploidy in a part; Type D showing aneuploidy in the majority of the sections and diploidy in a part; and Type E showing aneuploidy in all sections with different DI in some parts. Ki-67 in cell nuclei was stained immunohistochemically for the 4 microns-thick paraffin section using MIB1 monoclonal antibody, and the Ki-67 index expressing the growth fraction was calculated. Ki-67-index (Mean +/- SD) of 4 cases in Type A showed 20.6 +/- 4.88, that of 16 cases in Type B showed 37.5 +/- 9.62, that of 2 cases in Type C showed 42.4 +/- 0.21; that of 26 cases in Type D showed 41.8 +/- 10.6 and that of 22 cases in Type E showed 41.7 +/- 8.58. Thus, the aneuploidy group (type B, C, D, E) revealed a significantly higher Ki-67 index than the diploidy group (Type A) (p < 0.01). In the predominantly diploidy group (Type A, C), the cases in Type C also revealed a significantly higher value than the cases in Type A (p < 0.01). Therefore, there seemed to be some difference in the Ki-67 index or proliferative activity of cancer cells in large-bowel carcinomas relating to the intratumor DNA ploidy distribution pattern.