New test improves detection of bladder cancer


Testing for a certain protein in urine was found to increase the accuracy for diagnosis of bladder cancer, according to a study in the February 16 issue of JAMA, a theme issue on medical applications of biotechnology.

Bladder cancer is the fifth most common malignancy in the United States, according to background information in the article. Early detection improves prognosis, treatment options, and quality of life. Although the 5-year survival rate is 95 percent when tumors are detected while they are confined to the mucosa (membrane), up to 25 percent of the approximately 60,000 bladder tumors predicted to be diagnosed this year will be detected after they have become invasive or metastatic, which lowers 5-year survival to approximately 48 percent and 10 percent, respectively. As a result, 13,000 Americans will die of bladder cancer this year.

A combination of methods is used for diagnosis of bladder cancer because no single procedure detects all malignancies. Urine tests are frequently part of an evaluation, but have either been nonspecific for cancer or required specialized analysis at a laboratory.

H. Barton Grossman, M.D., of M.D. Anderson Cancer Center, Houston, and colleagues investigated whether a new, point-of-care, noninvasive urine-based test for the protein NMP22 proteomic marker could improve detection of bladder cancer. The researchers compared the ability of this test to detect cancer with that of urine cytology (cells), which must be analyzed in a clinical laboratory. The study included 23 academic, private practice, and veterans' facilities in 10 states which enrolled 1,331 patients at elevated risk for bladder cancer (history of smoking and certain symptoms) from September 2001 to May 2002. Patients at risk for malignancy of the urinary tract provided a urine sample for analysis of NMP22 protein and cytology prior to cystoscopy (visual examination of the bladder using a special instrument that is passed through the urethra).

Bladder cancer was diagnosed in 79 patients. "We found that the NMP22 test is a useful adjunctive tool in the evaluation of patients at risk for bladder cancer and that it identified several malignancies missed by initial cystoscopy. Specificity of the NMP22 test was lower than for cytology (85.7 percent vs. 99.2 percent), but sensitivity was significantly greater (55.7 percent vs. 15.8 percent), with test results available during the patient visit," the authors write. "The proteomic marker detected 4 cancers that were not visualized during initial cystoscopy, including 3 that were muscle invasive and 1 carcinoma in situ." According to the article, the average Medicare reimbursement for voided cytology is approximately $56, compared with $24 for the NMP22 point-of-care assay.

"In conclusion, the NMP22 assay may be a useful adjunct to cystoscopy for diagnosing bladder cancer. Studies in different patient populations are necessary to further define the role of this assay in patients with risk factors and symptoms suggestive of possible bladder cancer," the researchers write.

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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