Analysis of the immunohistochemical expressions of p53, bcl-2 and Ki-67 in colorectal adenocarcinoma and their correlations with the prognostic factors

Abstract

CONTEXT: Search of tumors markers that allow treatment with higher survival rates, and indicate the response to treatment and recurrence of cancer OBJECTIVE: To analyze the immunoexpression of the proteins p53, bcl-2 and Ki-67 in colorectal adenocarcinoma and correlate them with the clinical-pathological prognostic factors. METHOD: Tissue microarray paraffin blocks were made from colorectal adenocarcinoma tissue resected from 82 patients who had undergone surgery but not chemotherapy or radiotherapy, at "Hospital São Paulo", São Paulo, SP, Brazil, between 2002 and 2005. Thin sections (4 µm) were subjected to immunohistochemical reactions, and immunoexpression staining scores were obtained. The scores were correlated with the degree of cell differentiation, staging, disease-free interval, recurrence, survival and specific mortality. The study variables were analyzed using the chi-square and Kaplan-Meier tests to investigate associations with the markers. The significance of the differences between the curves of the disease-free interval and survival was analyzed using the Logrank and Wilcoxon tests. RESULTS: The immunohistochemical expression of p53 was positive in 70 tumors (85.4%) and negative in 12 (14.6%). The expression of bcl-2 was positive in 26 (31.7%) and negative in 56 (68.3%). The expression of Ki-67 was positive in 62 (75.6%) and negative in 20 (24.4%). There was no statistically significant correlation between the expressions of these markers separately or in conjunction, in relation to the degree of cell differentiation, staging, disease-free interval, survival and specific mortality. In relation to recurrence, there was a statistically significant correlation with positive expression of Ki-67 (P = 0.035). CONCLUSION: The immunohistochemical expression of Ki-67 in colorectal cancer is associated with recurrence of this disease.