Flow cytometry versus urinary cytology in the evaluation of patients with bladder cancer.

We compared the roles of urinary cytology and flow cytometry in the evaluation of patients with bladder cancer in clinical practice situations at a large general hospital. Specimens included 105 bladder washings from patients being followed for urothelial carcinomas and 28 control washings from individuals undergoing cytoscopy for other reasons. Flow cytometry and cytology were performed on aliquots of the same specimen in all bladder cancer samples. When carcinoma was present at the time of specimen collection it was detected by positive cytology in 75 per cent and deoxyribonucleic acid aneuploidy in 78 per cent of the cases. Combination of flow cytometry and urinary cytology increased the diagnostic yield to 95 per cent. Flow cytometry was slightly more sensitive than urinary cytology for detection of abnormalities in specimens from noninvasive and untreated tumors but the only statistically significant difference between the 2 procedures occurred among specimens from treated invasive cancers in which flow cytometry was a less sensitive method than cytology. Abnormal deoxyribonucleic acid ploidy was documented in a few specimens from noncancer-bearing patients having diseases associated with high urothelial cell turnover rates but the concomitant urinary cytology was negative for neoplasia. When used in conjunction with urinary cytology, flow cytometry was a valuable procedure in the followup of patients with bladder cancer. The diagnostic yield with this combination was such that flow cytometry and cytology may be used to reduce the frequency of cystoscopy and biopsy during clinical management in selected situations.