Purpose: A number of urine based markers have been and are being investigated for the diagnosis and prognostication of urological conditions. A majority of these markers have been evaluated in urological neoplasms, particularly bladder cancer. The diagnosis of bladder cancer currently relies on identifying malignant cells in the urine and subsequently visualizing the tumor on cystoscopy. This diagnosis is further confirmed by transurethral resection or biopsy. While urine cytology is specific, it is not sensitive, especially for detecting low grade disease. This characteristic has prompted the search for more accurate markers of bladder cancer. In this review we critically examine the results of studies evaluating various markers for bladder cancer.
Materials and methods: The published literature on urine based markers for all urological diseases, particularly bladder cancer, was identified using a MEDLINE search and critically analyzed. The sensitivity, specificity, positive and negative predictive values of the various markers were compared. The benefit of using combined markers rather than a single marker was also analyzed from published reports.
Results: Most published literature on urine based markers for urological malignancies involve such markers for diagnosing and prognosticating bladder cancer. Hence, we focused mainly on urine based markers in bladder cancer. Most markers appear to have an advantage over urine cytology in terms of sensitivity, especially for detecting low grade, superficial tumors. However, most markers tend to be less specific than cytology, yielding more false-positive results. This scenario is more common in patients with concurrent bladder inflammation or other benign bladder conditions. However, there is reason to be optimistic about several new markers that appear to provide better specificity. Few urine based markers have been identified and investigated in other urological tumors.
Conclusions: Detecting bladder cancer using diagnostic markers still presents a challenge. A number of new markers are currently available that appear to be significantly more accurate than cytology. However, further studies involving a larger number of patients are required to determine their accuracy and widespread applicability for diagnosing bladder cancer. Urine based markers do not appear to have a significant role in the diagnosis or prognosis of other urological malignancies, such as prostate, kidney or testicular cancer.