Use of diagnostic categories in urinary cytology in comparison with the bladder tumour antigen (BTA) test in bladder cancer patients.

In recent years the use of diagnostic categories for extragenital cytology has increasingly been discussed as an approach to improve the quality of reports. Diagnostic categories reflect the adequacy of the materials for interpretation and the presence or absence of cancer cells. There is a tendency to add intermediate groups as qualifying probably malignant cases or findings associated with a serious cancer risk. Since 1971 we have added one of the following to the final diagnosis in all cases: unsatisfactory for cytological diagnosis, negative for cancer, repeat test suggested, suspicious of cancer, and positive for cancer. To evaluate whether diagnostic categories are useful for comparison of cytological results with those of an alternative test, cytological data were compared with the results of the Bard bladder tumour antigen (BTA) test in voided urine from 119 patients (76 with and 43 without bladder cancer). The diagnostic categories enabled us to calculate sensitivities and specificities of cytology based on different thresholds or decision levels. The BTA test had significantly higher sensitivity (79%) and lower specificity (60%) than urinary cytology with three different thresholds in cytology results (sensitivities: 16-43%, specificities: 81-100%). The present findings suggest that diagnostic categories improve comparison of cytologic results with those of alternative screening and diagnostic aids such as the BTA test.