DNA/RNA ratio in bladder cancer: a factor indicating the recurrence rate?

Flow cytometry (FCM) was used to monitor 24 patients receiving intravesical mitomycin C (MMC) therapy. The patients were selected for MMC therapy because of multiple low stage bladder tumours which had not been cleared by previous endoscopic management. The response to treatment was monitored with cystoscopy, cytology, mucosal biopsies and flow cytometry. Follow-up was for a minimum of 12 months and 19 patients (79%) remained free of tumour. Four patients developed recurrences 6 months after therapy (16.5%) and one showed no response. There were no partial responders. The flow patterns of the four patients who developed recurrence showed an increased RNA/DNA ratio; this was detected after the third MMC instillation and remained throughout the follow-up period. The patients who did not develop recurrence demonstrated either a 1:1 or decreased RNA/DNA ratio. The increased RNA/DNA ratio appears to precede cystoscopic, urine cytology or biopsy evidence of recurrence. If this is confirmed in a larger series it could be used to select patients at high risk for recurrence who would be suitable for alternative therapy.