Reduced Recurrence Of Low-Risk Non-Muscle-Invasive Bladder Cancer Is Associated With Low Urine-Specific Gravity

Objective To investigate the association between urine-specific gravity and oncological outcomes in patients with non-muscle-invasive bladder cancer. Methods We identified 433 primary non-muscle-invasive bladder cancer patients who underwent transurethral resection between 2002 and 2016. The association between urine-specific gravity and tumor recurrence was statistically evaluated. Results A total of 211 (48.7%) patients received adjuvant bacillus Calmette-Guerin therapy. During the median follow-up period of 60 months, 155 (35.8%) patients experienced at least one tumor recurrence. Of them all, 95 (21.9%) and 338 (78.1%) patients had high (>1.020) and low (<= 1.020) urine-specific gravity, respectively. The Kaplan-Meier curve suggested that recurrence-free survival was significantly lower in patients with a high urine-specific gravity; however, the multivariate analysis failed to show that urine-specific gravity is significantly associated with tumor recurrence. In 222 (51.3%) patients who had not received bacillus Calmette-Guerin therapy, the Kaplan-Meier curve also suggested that recurrence-free survival was significantly lower in patients with a high urine-specific gravity. Multivariate analysis showed that age >70 years (hazard ratio 1.69,P = 0.02), grade 3 tumor (hazard ratio 1.81,P = 0.03) and high urine-specific gravity (hazard ratio 1.87,P < 0.01) were independent risk factors for tumor recurrence. Conclusion High urine-specific gravity is an independent risk factor for tumor recurrence in non-muscle-invasive bladder cancer patients who have not received bacillus Calmette-Guerin therapy. Our results suggest that hydration status might have some clinical impacts on bladder tumor recurrence.