Ki-67 and p53 immunoreactive stain and early colorectal neoplasms

The aim of this work was to conduct a histopathological study of the different pathways of colorectal tumorigenesis by using Ki-67 and p53 immunoreactive stains. Between 1987 and 1993, 14,023 patients were investigated by colonoscopy at Akita Red Cross Hospital and several affiliated hospitals. Five hundred and sixty-five cases of early colorectal neoplasms identified in this population were used in the present study. Specimens were cut in half: one half was cut along the vertical axis, the other half along the horizontal axis to analyze the structure of glands which opened to the surface. They were stained with hematoxylin-eosin, Ki-67 and p53 immunoreactive stains. macroscopically, early colorectal neoplasms were classified into two types: protruding type and depressed type. The protruding type was mainly composed of branching glands. In contrast, the depressed type was almost completely composed of straight glands which opened to the surface. The Ki-67 positive ratio was almost equal. However, the p53 positive ratio was significantly different in the protruding type and the depressed type. The results suggest the existence of at least two pathways of colorectal tumorigenesis: one with the process of branching structure and one without the process of branching structure. Furthermore, there were clinical and immunohistochemical indications that the depressed type invades into deeper layers more rapidly than does the protruding type.