The Bard® BTA Test: Its Mode of Action, Sensitivity and Specificity, Compared to Cytology of Voided Urine, in the Diagnosis of Superficial Bladder Cancer

Abstract

Objectives: Application of immunocytology directed against antigens of urothelial tumor cells or tumor-associated breakdown products intends to improve the sensitivity of the diagnosis of superficial transitional cell carcinoma (TCC) of the urinary bladder. In this study, the mode of action, sensitivity and specificity of the Bard^® BTA test, detecting a tumor-associated release of a basement membrane complex, was addressed and compared with voided urine cytology (VUC). Results: Contrary to grade, a significant (p = 0.003) relationship between tumor stage and BTA test sensitivity was observed, being 23.8, 33.3 to 100% for Ta (n = 42), T1 (n = 6) to ≥T2 (n = 5), respectively. These data suggest an association between an increase of the BTA test sensitivity with an increase of basement membrane degradation or interruption. With regard to this mechanism, the BTA test may be of special importance for monitoring tumor progression or increase in tumor invasiveness. Detection of low-stage, low-grade tumors by noninvasive techniques remains a challenge. The sensitivity of the BTA test for the presence of TCC was 32.3%, while that of VUC was 17.7%, but in this study the difference was not statistically significant. Furthermore, the BTA test was not more effective in identifying the various tumor grades, stages or stage/grade groupings. However, dividing the patients in two groups of low risk (TaG1/TaG2) and high risk (TaG3 to ≥T2) leads to a significant (p = 0.008) increased sensitivity of the BTA test (27.3%) in detecting patients with low-risk tumors compared to VUC (3.0%). The specificity of the BTA test in patients with a history of TCC was 81.6%, while that of VUC was 98.9%. Conclusion: The sensitivity of the BTA test is at least equivalent to VUC and may be suited to monitor increase in stage in patients suffering from bladder carcinoma, but cannot replace cystoscopy in patients suspected for a bladder tumor.