Effect of Intravesical Instillation of Gemcitabine vs Saline Immediately Following Resection of Suspected Low-Grade Non–Muscle-Invasive Bladder Cancer on Tumor Recurrence: SWOG S0337 Randomized Clinical Trial

IMPORTANCE: Low-grade non–muscle-invasive urothelial cancer frequently recurs after excision by transurethral resection of bladder tumor (TURBT). OBJECTIVE: To determine whether immediate post-TURBT intravesical instillation of gemcitabine reduces recurrence of suspected low-grade non–muscle-invasive urothelial cancer compared with saline. DESIGN, SETTING, AND PARTICIPANTS: Randomized double-blind clinical trial conducted at 23 US centers. Patients with suspected low-grade non–muscle-invasive urothelial cancer based on cystoscopic appearance without any high-grade or without more than 2 low-grade urothelial cancer episodes within 18 months before index TURBT were enrolled between January 23, 2008, and August 14, 2012, and followed up every 3 months with cystoscopy and cytology for 2 years and then semiannually for 2 years. Patients were monitored for tumor recurrence, progression to muscle invasion, survival, and toxic effects. The final date of follow-up was August 14, 2016. INTERVENTIONS: Participants were randomly assigned to receive intravesical instillation of gemcitabine (2 g in 100 mL of saline) (n = 201) or saline (100 mL) (n = 205) for 1 hour immediately following TURBT. MAIN OUTCOMES AND MEASURES: The primary outcome was time to recurrence of cancer. Secondary end points were time to muscle invasion and death due to any cause. RESULTS: Among 406 randomized eligible patients (median age, 66 years; 84.7% men), 383 completed the trial. In the intention-to-treat analysis, 67 of 201 patients (4-year estimate, 35%) in the gemcitabine group and 91 of 205 patients (4-year estimate, 47%) in the saline group had cancer recurrence within 4.0 years (hazard ratio, 0.66; 95% CI, 0.48-0.90; P