Analysis of false-positive BTA STAT test results in patients followed up for bladder cancer

To evaluate the role of a positive BTA stat Test result in patients with negative cystoscopic findings.

Five hundred one consecutive patients in follow-up for bladder cancer were studied. A voided urine sample was obtained before cystoscopy and split for culture, cytology, and BTA stat testing. In the case of a positive BTA stat Test, but negative cystoscopic findings, patients underwent additional investigations.

Of 501 patients, 133 (26.5%) had bladder cancer recurrence at cystoscopy, of which the BTA stat Test detected 71 (53.4%); only 21 of the cases (17.9%) were detected by cytologic examination. Of the remaining 368 patients with no visible tumor at cystoscopy, 96 (26.1%) had a positive BTA stat Test result. Fifty-five of those (57.3%) underwent intravenous urography or renal ultrasound and random biopsies, and an additional 9 recurrences (16.4%) were detected. Of those 46 patients who had a true false-positive BTA stat Test, 3 (3 of 43, 7.0%) had recurrence at the next follow-up cystoscopy, 4 (8.7%) had a urine infection, and 8 (17.4%) had ongoing intravesical instillations; the latter two percentages were significantly higher than among those with true-negative BTA stat Test results (0% and 6.8%, respectively).

Patients with a positive BTA stat Test result but negative cystoscopic findings have about a 16% risk of an undetected recurrence. False-positive results may be due to present instillation treatment and urine infection, and the predictive value of a BTA stat Test for subsequent recurrence seems relatively low.