P53 EXPRESSION, PLOIDY AND PROGRESSION IN PT1 TRANSITIONAL-CELL CARCINOMA OF THE BLADDER

Objective To investigate a potential role for overexpression of the p5 3 protein in the identification of pT1 bladder tumours destined to pro gress. Patients and methods The protein expression of the tumour suppr essor gene p53, nuclear ploidy and tumour grade were studied in 25 pat ients with pT1 bladder tumours. Follow-up data was available for 21 tu mours over a 10 year period, p53 expression was determined by immuno-h istochemistry on paraffin embedded sections and now cytometry was perf ormed on cell suspensions derived from the same blocks. Results Ten of 21 (48%) tumours progressed to muscle invasive disease. Nuclear stain ing for the protein was seen in 16 (64%) tumours and of these nine (56 %) progressed. All tumours with abnormal DNA content and all high grad e tumours demonstrated overexpression of p53. Significantly more patie nts with high levels of p53 expression (> 10% nuclear staining) progre ssed compared With tumours with less than 10% of nuclei staining (P = 0.007). However, grade was the mast specific predictor of progression (100%), with all grade 3 tumours progressing and grade was also the mo st significant prognostic indicator in terms of survival (P = 0.025). Conclusion Tumour grade is likely to remain as the most useful aid to management decisions in pT1 bladder tumours.