Screening for urothelial malignancies by cytologic analysis and flow cytometry in a community urologic practice: a prospective study.

A prospective study was initiated to compare the ability of flow cytometry and cytologic analysis to detect malignant cells in urine obtained at the time of cystoscopy. The population studied consisted of patients from general urologic practices who were undergoing cystoscopy in a single community hospital. Over a 1-yr period, 335 specimens from 317 patients were studied. Nineteen biopsy-proven urothelial malignancies were identified. Cytologic examination of urine obtained at the time of cystoscopy was positive in seven of these cases, and an aneuploid population of cells was identified by flow cytometry in three cases. All three cases of high-grade transitional cell carcinoma and carcinoma in situ were correctly identified by the combination of cytologic examination and flow cytometry; however, only four of 16 low-grade superficial papillary transitional cell carcinomas were recognized cytologically, with only one being aneuploid. The combination of cytologic analysis and flow cytometry did not increase the diagnostic sensitivity above that achieved with cytologic testing alone (overall sensitivity, 37%). We conclude that flow cytometry and cytologic analysis, either individually or in combination, are too insensitive for use in a routine screening program for urothelial malignancy in a community hospital setting because of the inability of either method to detect low-grade transitional cell carcinomas reliably.