Marker in Urine May Detect Bladder Cancer
According to a recent article published in the Journal of the American Medical Association (JAMA), levels of activity of the enzyme (protein) telomerase in urine may be an effective and non-invasive marker to detect bladder cancer. Further testing is necessary to confirm these findings.
Incidence of bladder cancer is common; approximately 55,000 new cases are diagnosed in the US?each year. Superficial bladder cancer refers to cancer that has not spread to muscles of the bladder or nearby lymph nodes. Recurrence of superficial bladder cancer is common and often involves cancer invading the muscle of the bladder. Surgery is then required to remove the cancer.
Patients who have undergone initial treatment for superficial bladder cancer often receive follow-up cystoscopies to detect a recurrence. During a cystoscopy, a physician places a lighted tube into the bladder to search for abnormal areas of tissue that indicate cancer. Since the cystoscope must be inserted into the bladder, cystoscopy is an invasive procedure?a notable limitation of this test.
A less invasive means of detecting bladder cancer recurrence is urinary cytology. With urinary cytology, a pathologist examines cells from a urine sample in order to find cancer cells that have been shed from the wall of the bladder. Urinary cytology, however, misses a fairly high proportion of low-grade (less aggressive) cancers. Given the limitations of both procedures, researchers are exploring tests that are less invasive than cystoscopy and more accurate than urinary cytology.
The enzyme telomerase is responsible for the replication of cells. A test referred to as a telomeric repeat amplification protocol (TRAP) assay can measure the activity of telomerase in voided urine.
Researchers from Italy recently conducted a clinical trial to evaluate the accuracy of TRAP in the detection of bladder cancer. This trial included 218 men; 84 participants were healthy and 134 had been diagnosed with bladder cancer. Results from TRAP were compared with results from a cystoscopy.
TRAP results were promising:
- 90% of bladder cancers were detected.
- TRAP accurately distinguished between cancerous or non-cancerous conditions in 88% of results.
- TRAP accurately distinguished between cancerous or non-cancerous conditions in 94% of results in men under 75 years of age.
The researchers concluded that TRAP is a highly accurate and noninvasive way of detecting bladder cancer in men. The authors state that TRAP may be feasible in men who are at a high-risk of developing bladder cancer, such as smokers or those who have been previously diagnosed with superficial bladder cancer. Patients at a high risk of developing bladder cancer may wish to speak with their physician regarding their individual risks and benefits of participating in a clinical trial further evaluating TRAP or other novel screening methods. Sources of information regarding ongoing clinical trials include the National Cancer Institute (www.cancer.gov).
Reference: Sanchini M, Gunelli R, Nanni O, et al. Relevance of Urine Telomerase in the Diagnosis of Bladder Cancer*. Journal of the American Medical Association.* 2005; 2005;294:2052-2056.