Fruit and vegetable intake and the risk of recurrence in patients with non-muscle invasive bladder cancer: a prospective cohort study

INTRODUCTION: There is some evidence that greater consumption of fruit and vegetables decreases the risk of bladder cancer. The role of fruit and vegetables in bladder cancer recurrence is still unknown. OBJECTIVE: The role of total fruit and vegetable intake in relation to the risk of developing bladder cancer recurrence in a prospective cohort study. METHODS: 728 patients with non-muscle invasive bladder cancer (NMIBC), who completed self-administrated questionnaires on fruit and vegetable intake at time of diagnosis (over the year before diagnosis) and 1 year after diagnosis, were included. Hazard ratios and 95% confidence intervals were calculated by multivariable Cox regression for developing recurrent bladder cancer in relation to fruit and vegetable intake. RESULTS: During 2,051 person-years of follow-up [mean (SD) follow-up 3.7 (1.5) years], 241 (33.1%) of the included 728 NMIBC patients developed a recurrence of bladder cancer. The sum of total fruit and vegetables before diagnosis was not related to a first bladder cancer recurrence (HR 1.07; 95% CI 0.78–1.47, p = 0.66). No association was found between greater consumption of fruit and vegetables over the year before diagnosis and the risk of developing multiple recurrences of bladder cancer (HR 1.02; 95% CI 0.90–1.15, p = 0.78). Among the remaining 389 NMIBC patients who reported on fruit and vegetable intake 1 year after diagnosis, no association was found between greater consumption of fruit and vegetables and a first recurrence of bladder cancer (HR 0.65; 95% CI 0.42–1.01, p = 0.06) nor with multiple recurrences of bladder cancer (HR 1.00, 95% CI 0.85–1.18, p = 1.00). Similar results were obtained when investigating the association between total intakes of fruit and vegetables separately and bladder cancer recurrence. CONCLUSION: Results from this study did not indicate a protective role for total fruit and vegetables in the development of a recurrence of NMIBC. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s10552-018-1029-9) contains supplementary material, which is available to authorized users.