Filter immunocytology: methodologic evaluation of a new assay for the diagnosis of urothelial cancer.

Objective: Several investigators have demonstrated the high sensitivity of immunocytology in the diagnosis of transitional cell carcinoma (TCC). A new technique, designated "filter immunocytology" (FLIC), simplifies the technique of quantitative immunocytology, considerable decreases assay time and increases the percentage of assessable specimens.

Study Design: Voided urine samples were obtained from 89 patients without evidence of TCC and from 91 patients with histologically proven TCC. The cells were transferred onto a polycarbonate membrane. Immunostaining was performed using monoclonal antibody. Due ABC 3, directed against a differentiation antigen on urothelial cells. Specimens containing > 35% positive urothelial cells were regarded as abnormal.

Results: Of 153 specimens 180 (85%) were assessable. The investigation of 76 specimens from control patients and 77 from patients with TCC yielded a specificity of 86% and a sensitivity of 75%, respectively. Sensitivity did not correlate with tumor grade. Despite high interobserver and intrapatient variations regarding the amount of antigen-positive cells, a concordant attribution to either "normal" or "abnormal" was made in > 95% of cases. Intraobserver variation was small and did not influence the test result.

Conclusion: These results suggest that FLIC assay may be a valuable adjunct to conventional cytology. A careful prospective investigation appears to be worthwhile to further define the indications for this technique.