Surveillance for recurrent bladder cancer using a point-of-care proteomic assay

Context At least 50% of patients with a history of bladder cancer have recurrences, so rigorous surveillance is necessary. Cystoscopy is standard but can fail to detect some bladder cancers, so a urine test is frequently part of the evaluation. Objective To investigate whether a point-of-care proteomic test that measures the nuclear matrix protein NMP22 in voided urine could improve detection of recurrence during monitoring of patients with a history of bladder cancer. Design, Setting, and Patients From September 2001 to February 2002, 23 academic, private practice, and hospital facilities in 9 US states prospectively enrolled 668 consecutive patients with a history of bladder cancer in this cross-sectional study. Patients provided a voided urine sample for analysis of NMP22 protein and cytology prior to cystoscopy. Main Outcome Measures Diagnosis of bladder cancer recurrence, based on cystoscopy with biopsy, was accepted as the reference standard. The performance of the NMP22 test was compared with voided urine cytology as an aid to detection. Testing for the NMP22 tumor marker was conducted in a blinded manner. Results Bladder cancer was diagnosed in 103 patients. Cystoscopy alone identified 91.3% of the cancers (94/103; 95% confidence interval [CI], 84.1%-95.9%). The combination of cystoscopy with the NMP22 assay detected 99.0% of the malignancies (102/103; 95% CI, 94.7%-100%; P=.005). The NMP22 assay detected 8 of 9 cancers that were not visualized during initial cystoscopy, including 7 that were high-grade. The sensitivity and specificity of the NMP22 test alone were 49.5% (51/103; 95% CI, 39.5%-59.5%) and 87.3% (493/565; 95% CI, 84.2%-89.9%), respectively, Voided cytology detected only 3 of the malignancies missed during initial cystoscopy and did not significantly increase the sensitivity of cystoscopy (94.2%; 95% CI, 87.7%-97.8%; P=.08). Conclusion The noninvasive point-of-care assay for elevated urinary NMP22 protein can increase the ability to detect recurrent bladder cancer, with test results available during the patient visit.