NMP-22: A Potential New Marker for Bladder Cancer
The role of NMP-22 in screening new patients for bladder cancer (incident cases) and in the follow-up of known patients with bladder cancer (prevalent cases) is an exciting new development. This new test uses a monoclonal assay -- manufactured by Matritech Inc. in Newton, Mass. -- to measure the level of a nuclear matrix protein (NMP). This test is a noninvasive, quantitative urine test that detects transitional cell carcinoma. NMP-22 is elevated in the urine of patients with bladder cancer, even in it's earliest stages.
While the test has FDA approval only for prevalent cases, we have explored it's utility in screening for new bladder cancer patients. Our preliminary data show that it augments the senstivity of an atypical cytology (see table). In 22 patients who had atypical screening cytologies and NMP value > 10, 14 (63 percent) had cytoscopic evidence of bladder cancer. Conversely, in 14 patients with atypical cytologies and NMP values < 10, only one of the 14 patients had cytoscopic evidence of bladder cancer. In the six patients who had a positive cytology for transitional cell carcinoma, all had NMP values > 10. Early results show that the higher-stage and -grade cancers elevate the NMP values the most, suggesting a quantiative correlation.
While our data on patients with prevalent bladder cancers are limited, we have confirmed the published data that an NMP value > 10 has a sensitivity that is twice that of the urinary cytology. Whether the sensitivity wil be high enough to replace an interval cytoscopy remains unclear. When the cutoff value for an abnormal NMP result was lowered to > 6.0 to increase the sensitivity, the number of false-positive results increased considerably.
Our laboratory, under the direction of Ashok Agarwal, Ph.D., is actively exploring other clinical situations that may find merit in using the NMP test. We are currently exploring the ability of the test to monitor upper-tract urothelial cancers and assess a patient's response to BCG. The test may also help discriminate which subset of patients should receive adjuvant intravesical chemotherapy following transurethral resection of a bladder cancer.
Center for Reproductive Medicine
The Cleveland Clinic
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Cleveland OH 44195