A comparative study of E-cadherin and stromelysin-3 expression in de novo and ex adenoma carcinoma of the colorectum.

An apparent exception to the colorectal adenoma-carcinoma carcinogenetic pathway is the so-called "de novo" carcinoma which has no evidence of adenoma in its vicinity. Despite the fact that they are often quite small, these lesions appear to be more aggressive (i.e., greater likelihood of lymph-node metastases) than carcinomas that clearly arise from surrounding adenomas exadenoma carcinoma. The purpose of the present comparative immunohistochemical study was to compare rates of cell adhesion molecule (E-cadherin) and protease [stromelysin-3 (ST-3)] expression in groups of de novo (n=64) and ex adenoma (n=42) lesions in order to see whether their more aggressive behavior is associated with decreased cell adhesion and increased protease expression. The rates of extensive ST-3 expression and decreased E-cadherin expression were significantly higher in the de novo group (P=0.014 and 0.005, respectively). Histopathologically, the de novo group also had a significantly higher percentage of cases with an infiltrative invasion pattern. These differences highlight the more aggressive phenotype of the de novo colorectal carcinoma and fit with their greater invasive potential.