IMMUNOHISTOCHEMICAL EXPRESSION OF P53 ONC OPROTEIN IN LARGE-BOWEL ADENOMAS AND CARCINOMAS

Background: Colorectal carcinoma is the sixth cause of death in Chile. Half of malignant tumors in humans have genetic alterations in proton cogenes, tumor suppressing genes or both. One of the most frequent alt erations is that involving p53 tumor suppressor gene. Aim To study usi ng immunohistochemical methods, alterations in p53 gene expression in colorectal carcinomas and adenomas. Material and methods: A random sam ple of 28 large bowel adenomas and 44 carcinomas was studied. Determin ation of p53 protein was made with an immunohistochemical method using monoclonal antibodies. patients were followed for a mean of 36 months (range 1 to 100 months). Results: p53 immunostaining was obtained in one adenoma (3.5%) and in 18 carcinomas (41%, p = 0.01). There were no differences in survival during follow up, between cancer patients tha t expressed or did not express p53 protein. Conclusions: About half of colorectal tumors have immunohistochemical expression of p53 protein, as published aboard. We did not find a prognostic value for this prot ein in our sample.