PROBLEMS WITH P53 IMMUNOHISTOCHEMICAL STAINING - THE EFFECT OF FIXATION AND VARIATION IN THE METHODS OF EVALUATION

The availability of antibodies which recognise p53 protein in paraffin -embedded tissue has created the opportunity to use immunohistochemist ry to study the expression of p53 in a wide variety of clinical materi al. In this paper we have investigated the relationship between the ty pe of fixative and the pattern of p53 staining in mammary carcinoma. O ptimal results were obtained from breast tissue fixed in phenol formol saline, methacarn or cold formol saline with positive staining for st abilised p53 protein occurring in 69/95 (73%) cases studied. Care must be taken in the interpretation of these results since positive staini ng for p53 protein is not always indicative of mutation of the p53 gen e. Furthermore, a range of staining patterns is seen in mammary carcin omas, making interpretation difficult. Assessment of staining needs to be standardised in order that different studies can be compared. Howe ver, in breast carcinoma, p53 immunohistochemistry appears to give inf ormation relating to tumour grade and, independently, to prognosis.