[Ki-67 and p53 expressions versus differentiation degrees of colon adenocarcinoma]

The colon carcinoma prognostic is evaluated with respect to four categories of factors established by College of American Pathologists Consensus Statement 1999, among which a series of molecular markers is also included. Our study aimed to develop semiquantitative analysis of the immunohistochemistry pattern for proliferation and apoptosis markers, as well as of their connections with the histopathology subtypes of colon adenocarcinoma.

The group of study included 5 cases of well-differentiated adenocarcinoma, 5 cases of moderately differentiated adenocarcinoma and 5 cases of poor differentiated adenocarcinoma. The Ki-67 and p53 antibodies (DAKO) and the streptavidin-biotin method (LSAB Kit, DAKO) were used for the immunohistochemical staining. The semiquantitative analysis provided the Ki-67 and p53 indices, and subsequently their values were statistically correlated with the histologic differentiation degrees.

All the cases presented positive immunohistochemistry reaction for Ki-67, the Ki-67 index varying on a large scale, between 5% and 95%. For p53, 10 out of the 15 cases (66%) presented positive immunohistochemistry reaction, with the index value between 22% and 95%, and 5 cases were negative. The statistical analysis revealed no significant difference between the Ki-67 indices of the three histopathologic subtypes (p = 0.674), whereas important differences appeared for the p53 indices (p = 0.007).

Our findings support the correct understanding of the role played by the immunohistochemical markers, in the sense of the risk involved by considering a pre-definite hierarchy in the diagnosis strategy.