CARCINOGENESIS OF COLON-RECTAL CANCER

Abstract

Objective: Carcinoma of the rectal colon begins as a small neoplastic polyp which gradually increases in size and, after passing through various degrees of dysplasia, develops into an overtly malignant carcinoma. Clinical experience suggests that patients may be divided into subgroups based on the aggressivity of the tumour. The genetic mutations associated with colorectal cancer have been studied and it is known that the genes primarily responsible for biologica1 changes in the tumour cell, in the early stages, are APC, hMSH2, k-ras2 and, in particular, p53. Indeed, the mutation at the level of gene p53 has been recognized as the most common mutation in tumour cells. The aim of this study was investigate the role of p53 and CD34 in colorectal cancer.

Methods: We studied p53 positivity using immunohistological methods and compared our results with the site, stage (using the TNM system) and histological grade of the tumour. We evaluated CD34 positivity using the same methods in order to detect and quantity the presence of angiogenesis in colorectal cancer.

Result: P53 was found to be markedly raised in the T3 stage of colorectal cancer, while its expression was decreased in stage T2 and stage T1 carcinomas and it was not detectable in adenomas. These results suggest a close correlation between the tumour stage and the expression of p53. An analogous correlation was found between CD34 expression and angiogenesis.

Conclusion: The overexpression of p53 in epithelial cells and raised angiogenesis (as reflected in CD34 levels) in stromal cells could represent useful prognostic factors in the management of colorectal cancer.