Immunohistochemical detection of the
nuclear antigen recognised by the
monoclonal antibody Ki67,
DNA polymerase alpha, and the
proliferating cell nuclear antigen (
PCNA), and histochemical staining for the argyrophilic
proteins associated with the nucleolar organizer regions (AgNOR) were carried out on histological sections from 107 colorectal
adenomas containing invasive
carcinoma (
ACIC), including 7 with regional
lymph node metastases. Separate evaluations were made for fields corresponding to
adenoma with low-grade dysplasia,
adenoma with high-grade dysplasia and early
cancer. The same techniques were also employed in 20 cases of normal mucosa and 20 advanced
carcinomas. The mean percentages of Ki67,
DNA polymerase alpha, and
PCNA-positive nuclei and the number of AgNOR per nucleus progressively increased along the sequence from normal mucosa via low-grade and high-grade dysplasia
adenoma to advanced
cancer, whereas the early
cancer values were not significantly different from those in the low-grade dysplasia areas. No significant difference in
PCNA positivity and number of AgNOR were noted in
ACIC with and without
lymph node metastases. It is suggested that the decrease in proliferative activity thus revealed in early
cancer may be due to changes in the submucosa microenvironment caused by invasion, and that the metastatic potential of an early
colorectal cancer cannot be correlated to such activity.