NMP22 is a sensitive, cost-effective test in patients at risk for bladder cancer

The early diagnosis of bladder cancer is central to its effective treatment. This study was designed to determine the clinical use of NMP22 as a urinary marker for the early detection of transitional cell carcinoma of the bladder in patients with hematuria or other indications at risk for malignancy. The sensitivity and specificity of the NMP22 test were compared with urinary cytology, and the results of both tests were then compared to cystoscopic findings. We also determined if NMP22 provided a cost advantage over our current modalities in our patient population.

Each patient submitted a single voided urine which was divided in 2 parts, of which 1 was stabilized with the NMP22 urine collection kit and 1 was preserved in the appropriate cytology medium for cytopathological testing. All patients provided the urine samples before cystoscopic examination. Of the 330 patients 114 (34.5%) presented with microscopic hematuria and 66 (20.4%) with gross hematuria. Other indications for cystoscopy included atypical cytology or unexplained voiding symptoms refractory to medical therapy.

There were 18 patients with biopsy confirmed bladder cancer and 312 with benign conditions of the bladder. Median NMP22 value for the malignant bladder tumors was 31.6 units per ml. (95% confidence interval 13.4 to 90.9) and 4.3 units per ml. (3.8 to 4.8) for benign conditions of the bladder. The urinary NMP22 values in the bladder cancer group were significantly higher than those in the benign condition group (p <0.001). The sensitivity of NMP22 was 100% with a specificity of 85% at a reference value of 10.0 units per ml., while cytology had a sensitivity of only 33% and specificity of 100%. Given a negative predictive value of 100% for NMP22, a cost savings of $28,302 to $111,072 (depending on the type of insurance carrier) would have been achieved if it was used alone as the indication for cystoscopy.

This study indicates that urinary NMP22 is a simple, noninvasive, cost-effective marker for the detection of bladder cancer.