Evaluation of Immunoreactivity of p53 in Colorectal Adenocarcinomas

摘要

Introduction: Colorectal Cancer (CRC) is regarded as one of the most widespread malignant tumor in the world. The p53 tumor suppressor gene is the most commonly mutated gene in human cancers and is a frequent abnormality in CRC. Patients with abnormal p53 might be at increased risk of death, due to increased aggressiveness of the disease.Aim: To study the immunohistochemical expression patterns of p53 in colorectal adenocarcinomas and to evaluate the relation between p53 status and various clinico-pathologic parameters.Materials and Methods: Fifty paraffin-embedded tissue blocks of colectomy specimens were used in this study (prospective and retrospective). Data like age at diagnosis, gender, type of surgery, tumor location, tumor size, histological type, tumor grade, depth of invasion, number of lymph nodes resected and number of lymph nodes with metastases were analysed. Two sections of 4 micrometer thickness were taken from each paraffin embedded tissue block. First section was taken for Hematoxylin and Eosin (H&E) stain and other one for immunohistochemistry (anti-p53 monoclonal antibody) by using Novolink Polymer Detection system.Statistical Analysis: The correlation between p53 protein overexpression and each variable was evaluated using Chi-square analysis.Results: The p53 staining was positive in 88.0% (44/50) of the cases. Out of the 50 cases, 06 cases were negative, 12 were weekly (+), 12 moderately (++), and 20 intensely (+++) positive for p53 protein overexpression. The p53 expression was correlated with histological grade 2 of the tumor, with majority of the tumors showing intense positivity for p53 protein (p= 0.001). However, there was no significant association between p53 protein expression and other clinicopathologic variables such as age, gender, site of tumor, pathologic type, pT stage and pN stage of the disease.Conclusion: The p53 mutation plays an important role in development of colorectal carcinoma as p53 protein over expression is noted in majority of the patients. Assessment of p53 protein expression could be a useful tool to identify patients who might benefit from adjuvant therapy.