Detecting human bladder carcinoma cells in voided urine samples by assaying for the presence of telomerase activity.

BACKGROUND

In an attempt to find a more sensitive and specific noninvasive assay for the detection of bladder carcinoma, the authors assayed exfoliated cells from patients' voided urine for the presence of telomerase, an enzyme that maintains a cell's chromosomal length and is thought to be active in the transformation of normal somatic cells into immortal human tumor cells.

METHODS

The authors used a polymerase chain reaction (PCR)-based telomeric repeat amplification protocol (TRAP) assay to determine the presence of telomerase activity in voided urine samples from patients with known but yet untreated bladder carcinoma (n = 104) and from patients with hematuria of benign causes (n = 47). For 88 of the patients with bladder carcinoma, cytology was determined independently of the telomerase results or the pathology findings.

RESULTS

Of the 104 bladder carcinoma specimens, 88 (85%) tested positive for the presence of telomerase. Seventy-nine percent (23 of 29) of the Grade 1 tumors, 84% (32 of 38) of the Grade 2 tumors, and 87.5% (28 of 32) of the Grade 3 tumors were positive for telomerase activity. Five patients with carcinoma in situ (100%) were also positive. Telomerase activity was not found in 31 of 47 patients with bladder calculi, benign urethral stricture, benign prostatic hyperplasia, or inflammation. In the 16 patients (34%) who did have a false-positive result when tested for telomerase, all had either chronic or severe inflammation, including 1 patient with an inverted papilloma, 1 patient with cystitis cystica, and 1 patient with cystitis glandularis. However, for 35 normal, healthy volunteers whose voided urine samples were also assayed for the presence of telomerase activity, none was found. By comparison, only 51% (45 of 88) of the cytology samples from patients with bladder carcinoma yielded positive findings, whereas 49% (43 of 88) resulted in false-negative readings for tumors. Only 13% (3 of 23) of the Grade 1 tumors, 44% (14 of 32) of the Grade 2 tumors, and 82% (23 of 28) of the Grade 3 tumors were diagnosed by cytology. All five patients with carcinoma in situ were positive for cytology as well as for telomerase activity. When cytology was compared with the PCR-based telomerase assay in determining the presence of bladder carcinoma, the difference in the overall detection rates (85% for telomerase vs. 51% for cytology) was significant (P < 0.001). Furthermore, when telomerase activity was compared with cytology for low grade lesions (Grades 1 and 2), the difference in the detection rates (82% for telomerase vs. 31% for cytology) was also significant (P < 0.001).

CONCLUSIONS

Urinary cytology yields poor results for low grade tumors. This study shows the possible application of the telomerase assay in detecting bladder carcinoma, in particular low grade tumors, in voided urine samples.