PROGNOSTIC-SIGNIFICANCE OF P53 ABNORMALITIES IN COLORECTAL-CARCINOMA DETECTED BY PCR-SSCP AND IMMUNOHISTOCHEMICAL ANALYSIS

Abnormalities in the p53 tumour suppressor gene and in the expression of its protein are common in colorectal carcinoma, The prognostic sign ificance of these p53 abnormalities was studied in 66 patients with co lorectal cancer, followed for more than 10 years. Single-strand confor mation polymorphism (SSCP) analysis was used to detect alterations in exons 5-8 of the p53 gene, Paraffin sections were examined immunohisto chemically for p53 overexpression with the monoclonal antibody DO-7 (D ako) both with and without microwave antigen retrieval, Abnormalities of the p53 gene were found in 41 per cent of cases by SSCP analysis. O utcome was unrelated to SSCP abnormalities (P=0 . 19), except for the Dukes' A and B subgroup, where decreased survival was found in cases w ith abnormal SSCP (P=0 . 01). Overexpression of p53 protein was seen b y immunohistochemistry in 47 per cent of cases without, and in 52 per cent of cases with microwave antigen retrieval, Immunohistochemical ov erexpression of p53 protein either with or without microwave antigen r etrieval was an independent prognostic indicator of poor survival, The se results suggest that for routine purposes, immunohistochemical dete ction of the p53 protein product may be more useful than SSCP analysis of the encoding p53 gene in identifying those at high risk of colorec tal cancer recurrence and death.