Enzyme Test for Bladder Cancer May Promote Early Diagnosis

Measuring levels of the enzyme telomerase in urine may be a simple, inexpensive, and accurate way to detect Bladder cancer early, according to investigators here.

About 20% of Bladder cancer patients die each year, but chances of survival are good when the disease is diagnosed and treated in the early stage, the investigators said.

However diagnosis of Bladder cancer is often delayed because symptoms such as hematuria are intermittent and can be attributed to common, benign disorders such as urinary track infections, prostatitis, and renal stones.

As a result patients with such symptoms often are not screened for cancer with cystoscopy, the current gold standard for diagnosing Bladder cancer - but invasive and expensive.

For these reasons, and because urine cytology lacks sensitivity, especially for low-grade tumors, a better alternative is needed, the Italian research team said in the Oct. 26 issue of the Journal of the American Medical Association. Telomerase was chosen as a possible marker because elevated levels have been found in nearly all human tumor histotypes.

Bladder cancer is a malignant tumor growth within the bladder. Bladder cancers usually arise from the transitional cells of the bladder (the cells lining the bladder).

These tumors may be classified based on their growth pattern as either papillary tumors (meaning they have a wart-like lesion attached to a stalk) or nonpapillary tumors. Nonpapillary tumors are much less common, but they are more invasive and have a poorer prognosis.

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In a study of more than 200 men, the telomeric repeat amplification protocol (TRAP) achieved a sensitivity of 90%, which is equal to that of cytoscopy, reported Daniele Calistri, Ph.D., of the Morgagni-Pierantoni Hospital here and colleagues.

The TRAP test requires a small amount of urine and is noninvasive, inexpensive, and easy to perform, the researchers said. Furthermore, it is objective, reproducible, and not reliant on the expertise of a cytopathologist, they added.

The study included 218 men-84 healthy individuals and 134 patients with a first diagnosis of histologically confirmed Bladder cancer. Urine samples from all patients were processed for cytological diagnosis and TRAP assay. The TRAP assay, which was performed in a blinded fashion, was compared to urine cytology for ability to detect Bladder cancer.

Using a cutoff value of 50 arbitrary enzyme units, the sensitivity of the TRAP test was 90% (95% confidence interval=83%-94%) and its specificity was 88% (95% CI=79%-93%).

In a subgroup of patients 75 or younger, the sensitivity increased to 94% (95% CI=85%-98%).