Fluid intake and recurrence and progression risk of patients with non-muscle-invasive bladder cancer

To evaluate the association of pre- and post-diagnosis fluid intake with non-muscle-invasive bladder cancer (NMIBC) recurrence and progression risk.

Data were used from the multicentre prospective cohort study UroLife. Participants reported pre-diagnosis fluid intake at 6 weeks (food frequency questionnaire [FFQ]) (n = 1322) and post-diagnosis fluid intake at 3 and 15 months (FFQ and 4-day 24-h fluid diaries) (n = 1275) after diagnosis. Multivariable proportional hazard regression models were used to obtain hazard ratios (HRs) and 95% confidence intervals (CIs) for the association of fluid intake with risk of first and multiple recurrence(s) and progression.

During a median overall follow-up of 4.6 years, 474 patients had one or more recurrence and 142 had progression. A higher first recurrence risk was observed for patients with the highest pre-diagnosis fluid intakes (≥2300 vs 1500-1900 mL/day: HR 1.38, 95% CI 1.07-1.79), but not for those with the highest post-diagnosis fluid intakes. HRs were similar for multiple recurrence risk. For progression, each 150 mL/day increase in both pre- and post-diagnosis fluid intake was consistently associated with an increased risk (post-diagnosis [3 months] FFQ-based: HR 1.05, 95% CI 1.01-1.09 and diary-based: HR 1.04, 95% CI 0.99-1.09).

High fluid intakes may be associated with higher NMIBC recurrence and especially progression risk. These findings lack a clear explanation but may be related to extensive expansion of the bladder wall or urinary symptoms. Further research is warranted. Meanwhile, these findings do not support recommending high(er) fluid intakes to patients with NMIBC to decrease their recurrence or progression risk.