Abstract
BackgroundSeveral studies have investigated the relationship between dietary patterns and the risk of bladder cancer (BC) in different regions including Europe, the United States, and Asia, with no conclusive evidence. A meta-analysis was undertaken to integrate the most recent information on the relationship between a data-driven Western diet (WD), the Mediterranean diet (MD), and dietary-inflammatory-index (DII) and the risk of BC.MethodWe looked for published research into the relationship between dietary patterns and the incidence of BC in the PubMed/Medline, Cochrane Library, Web of Science, and Scopus databases up until February 2021. Using a multivariate random-effects model, we compared the highest and lowest categories of WD, MD and DII patterns and provided the relative risk (RR) or odds ratios (OR) and 95 percent confidence intervals (CIs) for the relevant relationships.ResultsThe analysis comprised 12 papers that were found to be suitable after scanning the databases. Both case–control (OR 0.73, 95% CI: 0.52, 0.94; I2 = 49.9%, n = 2) and cohort studies (RR 0.93, 95% CI: 0.88, 0.97; I2 = 63%, n = 4) found a substantial inverse association between MD and BC. In addition, although cohort studies (RR 1.53, 95% CI 1.37, 1.70; I2 = 0%, n = 2) showed a direct association between WD and BC, case–control studies (OR 1.33, 95% CI 0.81, 1.88; I2 = 68.5%, n = 2) did not. In cohort studies, we found no significant association between DII and BC (RR 1.02, 95% CI 0.93, 1.12; I2 = 38.5%, n = 2). In case–control studies, however, a strong direct association between DII and BC was discovered (RR 2.04, 95% CI 1.23, 2.85; I2 = 0%, n = 2).ConclusionThe current meta-analysis showed that MD and WD have protective and detrimental effects on BC risk, respectively. No significant association between DII and the risk of BC was observed. More research is still needed to confirm the findings. Additional study is warranted to better understand the etiological mechanisms underlying how different dietary patterns affect BC.Trial registrationProtocol registration number:CRD42020155353.Database for protocol registration: The international prospective register of systematic reviews database (PROSPERO).Data of registration: August 2020.
Highlights
Several studies have investigated the relationship between dietary patterns and the risk of bladder cancer (BC) in different regions including Europe, the United States, and Asia, with no conclusive evidence
We found no significant association between DII and BC (RR 1.02, 95% confidence intervals (CIs) 0.93, 1.12; I2 = 38.5%, n = 2)
There was no association between DII and BC risk
Summary
Several studies have investigated the relationship between dietary patterns and the risk of bladder cancer (BC) in different regions including Europe, the United States, and Asia, with no conclusive evidence. BC are non-muscle-invasive bladder cancer (NMIBC), a type that frequently recur and requires intensive treatment and follow-up measures posing a large burden on any national health care budgets [3]. Epidemiological studies introduced several factors that potentially influence the risk of bladder cancer. These factors include, sex, age, occupation, and smoking [3, 4]. According to the latest report from World Cancer Research Fund (WCRF), the evidence from epidemiologic studies on the above association is scarce and largely inconsistent [6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
