The Clinical Usefulness of Nuclear Matrix Protein-22 in Patients with Atypical Urine Cytology

PURPOSE: Difficulty exists in interpreting the significance of atypical urine cytology. This study was performed to assess the diagnostic utility of nuclear matrix protein-22 (NMP-22) testing when atypical cells are detected during urine cytology. MATERIALS AND METHODS: Among patients whose urine cytology was reported as atypical between January 2004 and December 2009, a total of 275 who also underwent NMP-22 testing were enrolled in the present study. These patients were further divided into the screening group (143 patients examined as outpatients for hematuria) and the follow-up group (132 patients followed up for previously diagnosed bladder cancer). The sensitivity, specificity, positive and negative predictive values, and accuracy were assessed for atypical cytology alone and in conjunction with NMP-22. RESULTS: Of the 275 patients exhibiting atypical urine cytology, cancer was confirmed in 85, yielding a positive predictive value of 30.9% (85/275). Of the 96 patients testing positive for NMP-22, 58 were diagnosed with bladder cancer. The positive predictive value in conjunction with NMP-22 was 60.4% (58/96). The sensitivity, specificity, negative predictive value, and accuracy were 68.2% (58/85), 80.0% (152/190), 84.9% (152/179), and 76.2% (210/275), respectively. Testing for NMP-22 in the screening and follow-up groups increased the positive predictive value from 30.0% (43/143) to 64.0% (32/50) and from 31.3% (42/132) to 56.5% (26/46), respectively; there was no significant difference between the screening and follow-up groups (p=0.106). CONCLUSIONS: When only cases with atypical urine cytology were examined, NMP-22 testing increased the detection rate of bladder cancer regardless of whether the test was used in screening hematuria or in following up patients.