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

Background: This study was designed to determine the clinical utility of NM P22 as a urinary marker for the early detection of transitional cell carcin oma (TCC) of the bladder in patients with hematuria or other indications fo r risk of malignancy. Its utility will be measured by sensitivity and speci ficity estimates as compared to cystoscopy. Since urine cytology is normall y collected in this population of patients, it will also be analyzed and co mpared to cystoscopy. Materials and Methods: Each patient submitted a singl e voided urine which was stabilized with the NMP22 urine collection kit or preserved in the appropriate cytology medium for cytopathologic testing. Al l patients provided the urine samples before cystoscopic exam. Of the 146 p atients, there were 43 patients with microscopic hematuria and 13 with gros s hematuria. Other indications for cystoscopy included unexplained or medic ally refractory voiding. There were 8 patients with biopsy confirmed bladde r cancer and 138 patients with benign conditions of the bladder. Results: T he 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 beni gn 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 statist ically 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 sen sitivity 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 pred ictive value, using NMP22 alone could have eliminated 124 cystoscopies with total savings ranging from $24,824 to $63,264 depending on the type of ins urance carrier Conclusions: This study indicates that urinary NMP22 is a us eful, cost-effective marker for the early detection of bladder cancer.