URINE CYTOLOGY: Is it Still the Gold Standard for Screening?

Abstract

Urine cytology remains the gold standard for bladder cancer screening. It is the test against which all others are compared when evaluating potential bladder tumor markers. The answer to whether urine cytology possess the optimal combination of sensitivity and specificity to retain consideration as the best screening device depends on the goals of the clinical practice. Urine cytology has excellent specificity with few false-positive cases. Its overall sensitivity is poor, but this drawback is explained for the most part by poor criteria for identifying well-differentiated, low-grade TCC. The natural history of such lesions is the occurrence of multiple superficial recurrences in 70% to 80% of patients, with only a minority (10% to 15%) progressing to muscle invasive or metastatic disease. Because patients with low-grade TCC are at low risk for progression, they are monitored primarily for the development of a subsequent tumor. One might argue that the detection of new low-grade lesions is of secondary importance to the early detection of disease progression. The performance characteristics of urine cytology in this regard are much improved. Urine cytology often results in the identification of high-grade malignant cells even before a cystoscopically distinguishable gross lesion is present. Routinely diagnosing grade I TCC may be clinically irrelevant. Ancillary techniques to improve the sensitivity of urine cytology have been insufficiently additive to have much clinical value. Several promising bladder tumor markers have been investigated as potential screening tools and are summarized in Table 3. BTA, nuclear matrix proteins, and fibrin/fibrinogen degradation products share lower specificities than urine cytology and may have high rates of false positivity. Telomerase is highly sensitive and highly specific but is not readily available as a point-of-service test. Hyaluronidase and hyaluronic acid are promising prognostic markers, but hyaluronidase does not detect grade I TCC. Early results from studies of this marker await verification. Combining some of these new markers may optimize their performance status, allowing the advantages of one test to correct the shortcomings of another. Likewise, their combination with urine cytology may prove beneficial. Although adding urine cytology has not increased the sensitivity of some point-of-service tests, few studies have addressed the effect on specificity. Until an obvious winner is declared in the race to find a bladder tumor marker, urine cytology will remain the gold standard screening method because of its comfortable familiarity.