Relevance of urine telomerase in the diagnosis of bladder cancer

Abstract

Context: The identification of new molecular markers is one of the most challenging goals for the early detection of bladder cancer because available noninvasive methods have neither sufficient sensitivity nor specificity to be acceptable for routine use.

Objective: To develop a relatively simple, inexpensive, and accurate test that measures telomerase activity in voided urine to apply to large-scale screening programs for bladder cancer detection.

Design, setting, and participants: Case-control study conducted in 218 men (84 healthy individuals and 134 patients at first diagnosis of histologically confirmed bladder cancer), frequency matched by age and recruited between March 2003 and November 2004 in Italy. Urine telomerase activity was determined using a highly sensitive telomeric repeat amplification protocol (TRAP) assay. Urine samples were processed for cytological diagnosis and TRAP assay. The diagnosis of bladder cancer was based on bioptic and cystoscopic examinations. The performance of the TRAP assay to detect urine telomerase activity was compared with urine cytology as an aid to early cancer detection. Quantification of urine telomerase activity was conducted in a blinded manner.

Main outcome measure: Sensitivity and specificity of TRAP to detect bladder cancer.

Results: Using a 50 arbitrary enzymatic unit cutoff value, we validated the results obtained in the pilot study. In the overall series, sensitivity was 90% (95% confidence interval [CI], 83%-94%) and specificity was 88% (95% CI, 79%-93%). Specificity increased to 94% (95% CI, 85%-98%) for individuals aged 75 years or younger. The same predictive capacity of telomerase activity levels was observed for patients with low-grade tumors or with negative cytology results.

Conclusions: The present validation study demonstrated the ability of urine telomerase activity levels to accurately detect the presence of bladder tumors in men. This test represents a potentially useful noninvasive diagnostic innovation for bladder cancer detection in high-risk groups such as habitual smokers or in symptomatic patients.