IMMUNOHISTOCHEMICAL ASSESSMENT OF GROWTH FRACTIONS IN COLORECTAL ADENOCARCINOMAS WITH MONOCLONAL-ANTIBODY KI-67 - RELATION TO CLINICAL AND PATHOLOGICAL VARIABLES

Immunostaining with monoclonal antibody Ki-67 (MAb Ki-67) has been employed to determine the growth fractions in a series of 139 primary adenocarcinomas of the large bowel. A wide range (18.9–71.4%; mean 39.4%; median 37.2%) in the percentage of Ki-67 reacting cells (Ki-67 index) was observed. The Ki-67 index was found to be unrelated to tumour stage, lymph node involvement, and presence of synchronous distant metastases. Mucinous carcinomas showed higher levels of Ki-67 reactivity than nonmucinous adenocarcinomas (P = 0.0003). Among non-mucinous adenocarcinomas a significant inverse correlation was demonstrated between the percentage of Ki-67 stained cells and the degree of differentiation (P = 0.002), and preservation of nuclear polarity (P < 0.001). Moreover, tumours of patients younger than 45 years were generally characterized by high numbers of proliferating cells. There was no correlation between Ki-67 index and the other clinical and pathological variables examined. In most cases small differences in Ki-67 reactivity were observed in different samples from the same tumour. These results demonstrate that immunohistochemical assay with MAb Ki-67 represents a simple and reliable method for the assessment of proliferative activity in colorectal adenocarcinomas and suggest that Ki-67 labeling may provide information of clinical relevance in the management of patients with large bowel cancer. © 1990, Gustav Fischer Verlag · Stuttgart · New York. All rights reserved.