Proliferative activity of colorectal adenocarcinoma: objectification of criteria of morphological evaluation

Abstract

Aim of the study. To analyze the correlation between proliferative activities determined on the basis of routine histological staining and immunohistochemical reaction to the nuclear antigen Ki-67 in colorectal adenocarcinomas. Methods. Thirty adenocarcinomas of the colon and rectum were retrospectively evaluated. Evaluation of proliferative activity was performed on serial histological preparations stained with hematoxylin and eosin and treated with antibodies to Ki-67. Calculation was carried out in the “hot spots” under four microscope high power fields (≈1 mm2). Results. An estimate of the Kendall rank correlation coefficient demonstrated a high degree of direct relationship between the number of mitoses counted by routine staining and proliferative activity estimated by the immunohistochemical method (τ = 0.708, p < 0.05). All observations on the dispersion diagram could be divided into three “cloud” clusters with similar values for Ki-67 with practically the same number of mitoses. Conclusions. On the basis of routine histological examination, it is possible to separate colorectal carcinomas from tumors with a low (1-2/mm2), moderate (3-5/mm2), and high (≥6/mm2) mitotic activity corresponding to the proliferation index values of Ki-67 <30%, 30%-50%, and >50%, respectively.