Surveillance with microsatellite analysis of urine in bladder cancer patients treated by radiotherapy.

Objectives: The interpretation of cystoscopy and cytology may be troublesome in bladder cancer patients previously treated by radiotherapy. We evaluated polymerase chain reaction (PCR)-based molecular cytology by microsatellite analysis (MA) and routine urine cytology (RUC) and expert urine cytology (EUC) as modes of surveillance for patients previously treated by radiotherapy with curative intent.

Methods: Eighty-one voided urine samples were obtained from 49 patients prior to cystoscopy and subjected to MA, RUC and EUC.

Results: During the follow-up period, six patients developed a recurrence. Sensitivity of MA, RUC and EUC was 83%, 50% and 33%, respectively. The specificity of MA, RUC and EUC was 93%, 85% and 97%, respectively. Cystoscopy was positive in 15 cases. Therefore, the positive predictive value of cystoscopy remained limited to 40%.

Conclusions: Next to recent studies demonstrating a high accuracy for MA in non-irradiated patients, our results indicate that molecular cytology by MA may also be a useful tool to improve the surveillance of bladder cancer patients previously treated by radiotherapy.