P53 and ploidy assessed by flow cytometry in bladder washings.

OBJECTIVE: To determine p53 expression in cells in bladder washings and to relate this to DNA content and clinical outcome. PATIENTS AND METHODS: Washings from 102 patients (41 with newly diagnosed superficial tumours [pTa and pT1], 49 with recurrent superficial tumours and 12 with carcinoma invading bladder muscle) were studied. In 39 cases, the primary bladder tumour was also analysed. The rates of tumour recurrence and progression were determined for the new superficial tumours and related to both p53 expression and DNA content. RESULTS: Cells positive for p53 were detected in 22 of 90 (24%) washings from patients with superficial bladder cancer. P53 expression correlated with tumour stage (P < 0.05), grade (P < 0.05) and abnormal DNA content (P < 0.05). The analysis of pure urothelial (cyto-keratin-positive) cells improved the detection of DNA abnormalities (P < 0.001). In 74% of cases where both washings and tumour were analysed, the results for DNA content agreed. Of 41 new superficial tumours, 27 (66%) recurred (11 were p53-positive, 16 were p53-negative, P = 0.221; 17 had abnormal DNA content, 10 were diploid, P = 0.069). Four patients progressed (one was p53-positive, P = 0.315 and all had abnormal DNA content, P = 0.072). CONCLUSION: P53-positive cells can be detected in washings using flow cytometry and were more commonly detected in association with aneuploid tumours. At short-term follow-up, flow cytometric analysis of DNA content in washings had greater predictive value than had p53 expression. Few washings contained aneuploid cells when the primary tumour contained diploid cells, although the collection of washings is a convenient way of sampling tumour cells.