Comparison of NMP22 BladderChek Test and Urine Cytology for the Detection of Recurrent Bladder Cancer

Abstract

To assess the clinical performance of the NMP22 BladderChek test, which is a qualitative test, and to compare it with voided urine cytology for the detection of recurrent bladder cancer. We also evaluated whether cystoscopy can be omitted from the surveillance protocol by combining the two tests. A total of 131 patients with a history of superficial transitional cell carcinoma of the bladder provided urine samples before a cystoscopic examination. Urine samples were assayed for the presence of NMP22 using the NMP22 BladderChek test and cytology was performed by a cytopathologist. Selected patients underwent a biopsy, with appropriate additional therapy. Results of the two tests were compared with that the results of cystoscopy, which was retained as the gold standard. For positive biopsies, the results of the NMP22 test and cytology were also correlated with the tumor stage and grade. Of the 46 recurrences detected by cystoscopy, the NMP22 test was positive in 39 cases and cytology in 19 cases. The sensitivity of the NMP22 test was 85%, which was significantly greater than that of cytology (41%). In particular, for low-risk tumors it was eight times more sensitive than cytology. The specificities of the NMP22 test and cytology were 77 and 96%, respectively. Combining the two tests increased overall sensitivity to 91%. However, 9% of the tumors were still not detected. The NMP22 BladderChek test is an in vitro qualitative test that is easily available and cheap; it can be performed by a urologist in the office and results can be interpreted within 30 min. The NMP22 test is superior to cytology for all grades and stages in the detection of recurrence in patients with a history of superficial bladder cancer. Our study indicates that the NMP22 test can be used as a substitute for urine cytology. The NMP22 test cannot replace cystoscopy, but it can be used as an adjunct to cystoscopy in the surveillance protocol for patients with superficial bladder cancer.