People with newly diagnosed non-muscle-invasive bladder cancer who reported higher fruit and vegetable intake three months after diagnosis had a lower hazard of a first recurrence, according to a Dutch cohort study. The same pattern appeared when researchers looked at people whose combined intake had increased between before diagnosis and the three-month assessment. That is an association, not evidence that changing diet prevented the cancer from returning.
The association appeared around three months
At three months, each additional 100 grams a day of total fruit and vegetable intake was associated with a hazard ratio of 0.91 for first recurrence. The 95% confidence interval ran from 0.85 to 0.99. A hazard ratio compares how quickly an event occurs over time. In this case, the estimate points to a lower rate of first recurrence at higher reported intake, while the confidence interval shows the range of statistical uncertainty around the estimate.
The intake-change analysis pointed in the same direction. Every 100 grams per day increase from prediagnosis to three months after diagnosis was associated with a hazard ratio of 0.90 for first recurrence, with a 95% confidence interval of 0.81 to 0.99.
How the study was set up
Researchers used UroLife cohort data from 22 hospitals in the Netherlands. Eligible participants were Dutch-speaking adults aged 18 to 80 with newly diagnosed, histologically confirmed Ta, T1 or Tis non-muscle-invasive bladder cancer who underwent TURBT. Diet was reported at six weeks and at three and 15 months after diagnosis.
Different analyses used different groups. The main recurrence analyses included 1,396 participants with prediagnosis diet information, 1,270 with postdiagnosis diet information and 910 with postdiagnosis plasma carotenoid measurements. For postdiagnosis analyses, median follow-up was 4.7 years. During follow-up, 466 participants had at least one recurrence, 139 had at least two recurrences and 153 had progression.
To estimate associations, the researchers used Cox proportional-hazards regression and reported 95% confidence intervals. This model compares the timing of events across exposure levels. The analyses adjusted for age, sex, smoking status, body mass index, physical activity and energy intake. Missing data were handled with multiple imputation by chained equations using 20 iterations, and complete-case analyses showed similar results.
Carotenoids showed no similar signal
Carotenoids did not show the same pattern. Total dietary and plasma carotenoids measured at three and 15 months were not associated with first recurrence, multiple recurrences or progression. The researchers also found no significant associations for any of the six individual carotenoids they examined.
At 15 months, the results were mixed. Vegetable intake showed only a borderline inverse association with first recurrence, with a hazard ratio of 0.88 and a 95% confidence interval of 0.76 to 1.02. Higher fruit intake was associated with increased progression risk, with a hazard ratio of 1.15 and a 95% confidence interval of 1.03 to 1.29. The unexpected progression signal may have been due to chance.
The findings remain tentative
Stratified analyses reported significant inverse associations only among women, former smokers, patients with less aggressive tumours and patients not treated with BCG. These were exploratory findings, so they do not show that the association was causal or that it is limited to those groups.
Taken together, the study suggests a possible link between higher fruit and vegetable intake soon after diagnosis and fewer first recurrences, but it did not find a clear overall association with prediagnosis intake, multiple recurrences or progression. Nor did it find an association for dietary or plasma carotenoids. Funding came from the Alpe d'HuZes/Dutch Cancer Society and the Dutch Cancer Society. The authors declared no conflict of interest.
Paper data and sources
Original title: Fruit and vegetable consumption, dietary and plasma carotenoids and risks of recurrence and progression in patients with non-muscle-invasive bladder cancer.
Authors: Alina Vrieling, Joann Kiebach, Michiel Balvers et al.
Journal/Repository: European journal of nutrition
Status: Peer-reviewed
First online: 2026-08-21
DOI: 10.1007/s00394-026-04079-4
Original paper · Full text