Expression of high p53 levels in colorectal cancer: a favourable prognostic factor

The expression of p53 protein was examined in a series of 111 colorectal ca ncer adenocarcinomas with a long follow-up. A quantitative luminometric imm unoassay (LIA) was used for the measurement of wild-type and mutant p53 pro tein in extracts from colorectal tumour cytosols, p53 being detected in 42% of the samples (range 0.0-52 ng mg(-1)). Using an arbitrary cut-off value of 2.7 ng mg(-1), 25% of the tumours were classified as manifesting high p5 3 levels. There was no association of p53 expression with patient age, sex, serum preoperative carcinoembryonic antigen (CEA) levels, tumour site and size, nodal status or TNM stage. Significant and independent correlation wa s found to exist between high p53 levels and prolonged disease-free surviva l (P = 0.05) at a median follow-up of 60 months. This survival advantage wa s most apparent among stage III cancer patients. The results from this stud y would suggest that expression of high p53 levels appear to be useful in s electing a group of colorectal cancer patients with a better prognosis.