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

This study was designed to determine the clinical utility of NMP22 as a urinary marker for the early detection of transitional cell carcinoma (TCC) of the bladder in patients with hematuria or other indications for risk of malignancy. Its utility will be measured by sensitivity and specificity estimates as compared to cystoscopy. Since urine cytology is normally collected in this population of patients, it will also be analyzed and compared to cystoscopy.

Each patient submitted a single voided urine which was stabilized with the NMP22 urine collection kit or preserved in the appropriate cytology medium for cytopathologic testing. All patients provided the urine samples before cystoscopic exam. Of the 146 patients, there were 43 patients with microscopic hematuria and 13 with gross hematuria. Other indications for cystoscopy included unexplained or medically refractory voiding. There were 8 patients with biopsy confirmed bladder cancer and 138 patients with benign conditions of the bladder.

The median NMP22 value for the bladder cancer malignancies was 27.8 U/mL (95% Confidence interval: 10.5-32.1 U/mL). The median NMP22 value for the benign conditions of the bladder was 3.25 U/mL (95% Confidence interval: 2.5-3.8 U/mL). The urinary NMP22 values from the bladder cancer group was statistically different (p < .000001 Mann-Whitney U test) than the NMP22 values in the benign conditions group. Using a reference value of 10.0 U/mL, the sensitivity of NMP22 was 100% with a specificity of 90%, while cytology had a sensitivity of 25% and a specificity of 100%. Due to its high negative predictive value, using NMP22 alone could have eliminated 124 cystoscopies with total savings ranging from $24,824 to $63,264 depending on the type of insurance carrier.

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