[Serum p53 antibody assay: evaluation in colorectal cancer]

Alterations of the tumor suppressor gene p53 and its protein synthesis is the most commonly observed genetic feature in human cancers. Direct diagnosis of the gene mutation using sequencing is the gold standard method. However, it requires advanced technology and is only performed in specialized research units.

Demonstration of intratumoral p53 protein accumulation using immunohistochemistry is a routine diagnostic technique. Serum detection of p53 antibodies using ELISA has been recently developed. It is an easily feasible and reproducible method for the diagnosis of p53 alterations due to self-immunization in some patients in response to intratumoral p53 protein overexpression. This phenomenon is inconstant (about one-third of the patients with a p53 gene mutation produce antibodies) and its mechanism is unclear. p53 Antibodies are found in 25% of the patients with colorectal cancer, independently of traditional tumor markers (carcinoembryonic antigen and carbohydrate antigen 19.9). The presence of these antibodies is not linked to the tumor stage. Since their ratios vary during the treatment, they might constitute a new tumor marker.

Early appearance of p53 serum antibodies during tumor development should make them useful for the detection of malignant transformation in patients with preneoplastic disease such as ulcerous colititis. Whether the presence of p53 antibodies in colorectal cancer patients has a prognostic significance requires further assessment.