REDUCED EXPRESSION OF RETINOBLASTOMA GENE-PRODUCT (PRB) AND HIGH EXPRESSION OF P53 ARE ASSOCIATED WITH POOR-PROGNOSIS IN OVARIAN-CANCER

Paraffin sections (n = 168, 27 benign, 16 low malignant potential [LMP ] and 125 malignant tumours) from epithelial ovarian tumours were eval uated immunohistochemically for expression of retinoblastoma gene prod uct (pRB) and p53 protein, and the relationship among pRB, p53 and cyc lin-dependent kinase inhibitor 2 (CDKN2) gene product p16(INK4A) (p16) was analysed, following our previous study of p16, Forty-one percent of the benign, 50% of the LMP and most (71%) of the malignant tumours showed high pRB expression, High expression of pRB (>50% pRB-positive cells) significantly correlated with non-mucinous histological subtype s. ReducedpRB expression, substage and residual disease were significa nt predictors for poor prognosis in stage I patients. All the benign a nd most of the LMP (81%) tumours were in either the p53-negative or lo w p53-positive category, but nearly half of the malignant tumours had high p53 expression. High p53 accumulation was found in non-mucinous, high grade and late stage tumours, For well-differentiated carcinomas, high p53 expression was a predictor of poor prognosis, However, even though high p53 expression was not associated With histological subtyp e, stage or the presence of residual disease, high p53 expression was not an independent predictor when all clinical parameters were combine d. For all ovarian cancers, a close correlation was found between high p53 and high p16 expression, The relationship between the expression of pRB and p16 depended on tumour stage. In stage I tumours, high pRB was associated with low p16 reactivity. On the other hand, most advanc ed tumours showed both high pRB and high p16 reactivity. (C) 1997 Wile y-Liss, Inc.