Role of urinary NMP-22 combined with urine cytology in follow-up surveillance of recurring superficial bladder urothelial carcinoma.

Objective: To determine efficacy and utility of NMP-22 in follow-up of bladder urothelial carcinoma (UC) and compare NMP-22 as a single evaluating test vs combination with cytology.

Study Design: Ninety-four consecutive urine cytology samples of bladder UC were identified. Patients received follow-up urine cytology, NMP-22 testing and cystoscopy with surgical biopsy.

Results: NMP-22 specificity was 100%, sensitivity 45%, positive predictive value (PPV) 100% and negative predictive value (NPV) 87%. NMP-22 showed lower sensitivity for high-grade lesions and higher for low-grade lesions. Cytologic diagnosis had a high inconclusive rate; when regarded as positive, it resulted in 75% sensitivity, 58% specificity, 33% PPV and 89% NPV. NMP-22 correctly classified 60% of false negative cases diagnosed by cytology with low-grade UC and clarified 27 inconclusive cytologic diagnoses. NMP-22 misclassified 9 cases as false negative, all with high-grade UC; all were correctly identified on cytology as true positive. Combined interpretation showed 90% sensitivity, 92% specificity, 75% PPV and 98% NPV.

Conclusion: NMP-22 complements cytology by its higher sensitivity for low-grade lesions; its values are not affected by bacillus Calmette Guérin therapy changes, which are limiting in cytology. Combined interpretation of NMP-22 and cytology shows promise as an effective, noninvasive method for surveillance of UC.