P53 in the clinic: A pathologist's view

Abstract

The p53 protein has many biological effects and a high prevalence of mutations in human cancer. Pathologists use this biomarker in several different situations, to help for the differential diagnosis of reactive/dysplastic/benign/malignant lesions, to better characterize malignant tumours, and to help in predicting response to treatment. p53 status of dysplastic and borderline lesions can most often be assessed only by immunohistochemistry (IHC) since these microscopical lesions are too small for advanced molecular assays. p53 protein status determined by IHC has however a smaller sensitivity compared to TP53 status assessed by gene sequencing. This explains why p53 as a biomarker remains not so widely used by pathologists except for several well-defined indications detailed in this chapter. P63, a member of the p53 family, is also frequently used in diagnostic pathology as a differentiation marker and will be discussed in this chapter.