RESUMO
AIMS: Xpert® Bladder Cancer Monitor is a urinary marker based on the evaluation of five target mRNAs overexpressed in patients with bladder cancer (BC). The aim of our study is to update our results regarding the diagnostic accuracy of the Xpert® Bladder Cancer Monitor test in the follow-up of patients with non-muscle invasive bladder cancer (NMIBC). METHODS: We conducted a prospective study on 1015 samples of 416 patients (mean age 72.2 ± 10.3 years) under follow-up for NMIBC. Patients underwent voided urinary cytology, the Xpert® Bladder Cancer Monitor test and cystoscopy and, if positive, a transurethral resection of the bladder. Xpert® Bladder Cancer Monitor was reported as negative or positive: cut-off total Linear Discriminant Analysis (LDA) = 0.5. RESULTS: We identified 168 recurrent tumours: 126 (75%) were low-grade (LG) and 42 (25%) high-grade (HG). Overall sensitivity was 17.9% for cytology, 52.4% for Xpert® Bladder Cancer Monitor and 54.2% for the two tests combined. The sensitivity of cytology increased from 6.3% in LG to 52.4% in HG tumours whereas Xpert® Bladder Cancer Monitor showed a sensitivity ranging from 42.9% in LG to 80.9% in HG tumours. Combined cytology and Xpert® Bladder Cancer Monitor yielded an overall sensitivity of 45.2% for LG and 80.9% for HG tumours. Overall specificity was 98.5% for cytology and 78.4% for Xpert® Bladder Cancer Monitor and 78.2% for the two tests combined. The area under the curve (AUC) for Xpert® Bladder Cancer Monitor was 0.71; stratifying the patients according to the European Association of Urology risk groups, the AUC was 0.69, 0.67 and 0.85 for low, intermediate and high risk, respectively (p = 0.0003). CONCLUSION: Our data confirm a significantly higher sensitivity of Xpert® Bladder Cancer Monitor than for cytology in a larger patient cohort. The test performed very well in terms of specificity but could not reach the high value of cytology. Along with voided urinary cytology the test could allow to reduce cystoscopies in follow-up patients, reducing discomfort to the patients and costs.
RESUMO
AIMS: Cystoscopy and urine cytology represent the gold standard for monitoring superficial bladder cancer (BC). Xpert BC Monitor is a new urinary marker based on the evaluation of five target mRNAs overexpressed in patients with bladder cancer. The aim of our study was to evaluate the diagnostic accuracy of Xpert BC Monitor in follow-up of patients with non-muscle invasive bladder cancer (NMIBC). METHODS: 230 patients were included in this prospective study. Xpert BC Monitor cut-off was set to 0.5. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of cytology, Xpert BC Monitor and their combination were calculated and compared with cystoscopy/histology. RESULTS: 52/230 patients showed a NMIBC recurrence, 45 low grade (LG) and 7 high grade (HG). Overall sensitivity was 11.5% for cytology, 46.2% for Xpert BC Monitor and 48.1% for the two tests combined. Sensitivity of cytology increased from 4.4% in LG to 57.1% in HG tumours whereas for the Xpert BC Monitor it was 40% in LG and 85.7% in HG tumours. Combined cytology and Xpert BC Monitor yielded an overall sensitivity of 42% for LG and 85.7% for HG. Overall specificity was 97.2% for cytology, 77% for Xpert BC Monitor and 75.8% for the two tests. CONCLUSIONS: Sensitivity for the Xpert BC Monitor Test was significantly higher than for cytology. The test performed very well in terms of specificity but could not reach the value of cytology, while PPV and NPV performed approximately the same for both tests.
