Use of a new tumor marker, urinary NMP22, in the detection of occult or rapidly recurring transitional cell carcinoma of the urinary tract following surgical treatment

Purpose: We evaluated the ability of an immunoassay for nuclear matrix protein 22 (NMP22* test kit) to predict the subsequent disease status of patients with transitional cell carcinoma of the urinary tract at approximately 10 days after transurethral resection of bladder tumor. Materials and Methods: A total of 90 patients with transitional cell carcinoma provided voided urine samples at least 5 days postoperatively. NMP22 was determined using a commercial test kit. At initial cystoscopic examination 3 to 6 months later the disease status was recorded, and the NMP22 values before and after transurethral resection of bladder tumor were compared. Results: Of 125 followup cystoscopic examinations (60 patients had 1, 26 had 2, 3 had 3 and 1 had 4 recurrences) transitional cell carcinoma was pathologically confirmed in 33. No malignancy was present at 79 examinations (if tumor was seen endoscopically, pathological evaluation indicated atypia, dysplasia or no abnormality). NMP22 values in these 2 populations were significantly different (malignancy median 20.81 units per mi. and no malignancy median 5.72 units per mi., Mann-Whitney U test for differences between 2 medians p = 0.00005). Of the 33 recurrences 23 (70%) had NMP22 values greater than the reference range (10 units per mi.). Additionally, NMP22 identified all 6 subjects (100%) who had invasive disease 3 to 6 months later. Of 72 patients with NMP22 less than 10 units per mi. 62 (86%) had no malignancy at subsequent cystoscopy. Conclusions: NMP22 was highly predictive of tumor status at followup cystoscopy. This quantitative, noninvasive assay, with high negative predictive value (86%) and sensitivity to detect malignancy (100% for invasive disease and 70% overall), may be a helpful adjunct to cytology and endoscopy for monitoring disease status after endoscopic tumor resection.