P53 expression, ploidy and progression in pT1 transitional cell carcinoma of the bladder.

OBJECTIVE: To investigate a potential role for overexpression of the p53 protein in the identification of pT1 bladder tumours destined to progress. PATIENTS AND METHODS: The protein expression of the tumour suppressor gene p53, nuclear ploidy and tumour grade were studied in 25 patients with pT1 bladder tumours. Follow-up data was available for 21 tumours over a 10 year period. p53 expression was determined by immuno-histochemistry on paraffin embedded sections and flow cytometry was performed on cell suspensions derived from the same blocks. RESULTS: Ten of 21 (48%) tumours progressed to muscle invasive disease. Nuclear staining for the protein was seen in 16 (64%) tumours and of these nine (56%) progressed. All tumours with abnormal DNA content and all high grade tumours demonstrated overexpression of p53. Significantly more patients with high levels of p53 expression (> 10% nuclear staining) progressed compared with tumours with less than 10% of nuclei staining (P = 0.007). However, grade was the most specific predictor of progression (100%), with all grade 3 tumours progressing and grade was also the most 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.