Colorectal cancer

The p53 gene is an important tumor suppressor gene located on the short arm of chromosome 17; somatic mutations of this gene are common in solid tumors. Its main task is to identify cells with significant DNA defects and coordinate cellular events that lead to cell cycle arrest in G 1 to allow time for repair or, if repair is not possible, apoptosis. Cells with mutant p53 proteins have reduced checkpoint activity and dysregulated cell proliferation. Given that avoiding apoptosis is crucial for cancer cells, p53 mutations are generally believed to have prognostic relevance. Loss of function of p53 is a late event in adenocarcinoma-carcinoma progression and has been identified in up to 60% of colon cancers. Mutations can be detected either at the protein level by immunohistochemical analysis or at the gene level by sequencing; the latter technique is considered more accurate but is more laborious. The presence of p53 mutations is also thought to be predictive of decreased cancer cell sensitivity to most chemotherapeutic agents, particularly fluorouracil. However, results from available studies, which have been retrospective and generally underpowered, are conflicting with respect to prognostic and predictive roles in colorectal cancer. the results of a large retrospective analysis of p53 mutations in an attempt to confirm the role of p53 as a prognostic and predictive factor in colorectal cancer.