The bladder tumor antigen (BTA) test compared to voided urine cytology in the detection of bladder neoplasms

Abstract

Purpose: Tests to detect recurrent bladder neoplasms are limited and none is consistently accurate. Recent studies suggest that the bladder tumor antigen (BTA) test, an agglutination reaction for basement membrane complexes, is superior to voided urine cytology in clinical practice. We compared BTA and voided urine cytology to bladder washings and cystoscopy, emphasizing diagnostic yield among patients with causes of basement membrane complexes other than bladder cancer.

Materials and methods: Random voided urine specimens from 67 patients with a history of bladder neoplasms were collected before cystoscopy and bladder washing. Urine also was obtained from 34 patients with inflammatory bladder conditions including 5 with a history of prostate cancer. Each urine was tested for BTA according to a commercial kit. Positive results were indicated by yellow on a test pad. Blinded to all other results, each urine and each bladder washing were examined microscopically, and a positive test had malignant/suspicious cells. Bladder biopsies were performed when endoscopic lesions were seen. Specimens were grouped into 4 categories: group 1--biopsy proved bladder neoplasm, group 2--history of bladder cancer but not biopsy proved, group 3--history of prostate cancer and group 4--no history of urological cancer.

Results: Voided urine cytology was positive in 54% of specimens from patients with biopsy proved bladder neoplasms compared to 29% for BTA. Relative yield for voided urine cytology versus BTA was not changed if all group 2 cases having a positive bladder washing and positive cystoscopy were assumed to have bladder cancer, nor was relative yield altered by subsequent short-term followup. Of voided urine specimens 14% from group 1 patients and 41% from group 2 patients had scant cells. Overall diagnostic yield was superior for bladder washing. False-positive BTA occurred in 7 of 34 patients with no history of urological or prostate cancer. There were no false-positive voided urine cytology interpretations in these groups.

Conclusions: BTA is not superior to voided urine cytology in detecting bladder neoplasms and may be limited by false-positive reactions in patients with other causes of basement membrane complexes in urine. Voided urine samples may be limited by high frequency of hypocellularity. Of 34 patients with a hypocellular urine specimen 4 had biopsy proved bladder cancer. Bladder washing yields best results but requires instrumentation. No test, including cystoscopy, is accurate always.