Total Fluid Intake and the Risk of Recurrence in Patients With Non-Muscle Invasive Bladder Cancer: A Prospective Cohort Study

Objectives: To investigate the role of fluid intake from beverages before and after a diagnosis of bladder cancer in relation to the risk of developing bladder cancer recurrence. Study Design: Prospective cohort study. Methods: 716 patients with non-muscle invasive bladder cancer (NMIBC), who received transurethral resection of a primary bladder tumour (TURBT) and completed self-administrated questionnaires on usual fluid intake from beverages at time of diagnosis (over the year before diagnosis) and during follow-up (over the year after diagnosis), were included. Multivariable Cox regression was used to calculate hazard ratios and 95% confidence intervals of developing recurrent bladder cancer in relation to the intake of total fluid, total alcohol, and individual beverages. Results: During 2,025 person-years of follow-up, 238 (33%) of the included 716 NMIBC patients developed one or more recurrences of bladder cancer. Total fluid intake before diagnosis was not associated with a first recurrence of bladder cancer when comparing the highest and lowest intake group (HR = 0.98, 95% C.I. 0.70-1.38, p = 0.91). Comparable results were obtained for total fluid intake pre-diagnosis and the risk of developing multiple recurrences of bladder cancer (HR = 1.01, 95% C. I. 0.87-1.19, p = 0.85). A total of 379 of the 716 patients reported on usual fluid intake within 1 year of diagnosis. No significant associations between total fluid intake 1 year after diagnosis and a first recurrence of bladder cancer were found when comparing the highest and lowest intake group (HR = 0.91; 95% C. I. 0.60-1.37, p = 0.65) or with multiple recurrences of bladder cancer (HR = 1.06; 95% C. I. 0.89-1.26, p = 0.54). In addition, total alcohol intake and individual beverages were not associated with bladder cancer recurrence. Conclusions: The results indicate that an individual's fluid intake from beverages is unlikely to have an important role in bladder cancer recurrence.