p53 immunoreactivity in breast cancer tissues does not deteriorate in stored paraffin sections

Immunohistochemistry has been used to detect stabilized p53 protein in many studies aimed at identifying prognostic and predictive factors for breast carcinoma, the results of which are directly compared despite the considerable variation in methodology. Recent reports have shown a diminution in p53 immunoreactivity in stored paraffin sections. We have compared p53 staining patterns in sections cut one day prior to assay with sections cut from the same block 4 years previously from 29 formal saline fixed breast cancer tissues. We found no statistical difference in p53 antigenicity between stored and newly cut sections (P = 0.96), 19 of the 29 (65%) showed the same proportion and intensity of cells staining. One case showed moderate p53 staining in the stored section but was negative in the newly cut sections. There was significantly less non-specific and cytoplasmic staining in the new sections. These results show that, contrary to recent reports, p53 antigenicity is not consistently diminished in optimally fixed stored sections if a sensitive immunohistochemical method is used with a robust, reliable p53 antibody.