The Use of Urine Mycobacterium tuberculosis Complex Polymerase Chain Reaction as a Predictive Factor for Recurrence and Progression After Intravesical Bacillus Calmette-Guérin Therapy in Patients with Non–muscle‑invasive Bladder Cancer

Abstract Background Intravesical bacillus Calmette-Guerin (BCG) instillation is a standard treatment for non–muscle-invasive bladder cancer (NMIBC); however, not all patients benefit from BCG therapy. Currently, no surrogate marker exists to predict BCG efficacy, and thereby, identify patients who will benefit from this treatment. Objective To evaluate the utility of urine Mycobacterium tuberculosis complex polymerase chain reaction (MTC-PCR) assay as a predictive marker for recurrence and progression following BCG therapy. Design, setting, and participants A prospective analysis was carried out for of intermediate- or high-risk NMIBC patients who received BCG instillation for the first time. Urine samples, for MTC-PCR assay, were collected at baseline and annually for up to 10 yr after the last BCG instillation, including induction and maintenance therapy. The first postoperative sample for MTC-PCR was taken at 1 yr from the last instillation. Outcome measurements and statistical analysis A survival analysis was performed using the Kaplan-Meier method, and risk factors for recurrence and progression after BCG treatment were assessed using Cox regression analysis. Results and limitations During follow-up (median: 57 mo), 468/521 samples (89.8%) were MTC-PCR positive, and 108/123 patients (87.8%) exhibited MTC-PCR positivity at least once. Five-year recurrence- and progression-free survival in patients who were not MTC-PCR positive was significantly lower than in patients who were MTC-PCR positive at least once (p  Conclusions Patients who were not MTC-PCR positive, even once after BCG therapy, were extremely likely to exhibit recurrence and progression. Urine MTC-PCR may be an extremely useful, noninvasive surrogate marker to predict recurrence and progression following BCG therapy. Patient summary Urine Mycobacterium tuberculosis complex polymerase chain reaction may be a novel biomarker capable of identifying patients at risk of recurrence and progression after bacillus Calmette-Guerin (BCG) immunotherapy.