Increased Inflammatory Potential of Diet Is Associated with Increased Risk of Bladder Cancer in an Iranian Case-Control Study

Abstract

Purpose: Various aspects of diet have been implicated to play a role in the etiology of bladder cancer. Studies examining this association have been conducted primarily in Western countries but none in Middle Eastern Countries.

Method: We examined the association between the dietary inflammatory index (DII^®) and bladder cancer in an Iranian case-control study. A total of 56 incident cases with a mean age of 60 years and 109 controls with a mean age of 57 years, attending the same hospital as the cases during the same time period, were recruited. The DII is a literature-derived index developed to determine the inflammatory potential of diet and was computed using a validated food frequency questionnaire. Logistic regression was used to estimate odds ratios, with DII fit as continuous and as a dichotomous variable.

Results: Multivariate analyses revealed that subjects with higher DII score (>–0.12) are at higher risk of bladder cancer [odds ratio (OR) = 2.46; 95% CI = 1.12–5.41, P value = 0.02)] compared to subjects with lower DII scores (≤–0.12). Stratified results showed stronger association was among current/ex-smokers (OR_{DII (>–0.12/≤–0.12)} = 3.30; 95% CI = 1.07–10.16).

Conclusion: These data suggest a pro-inflammatory diet may be a risk factor for bladder cancer among Iranians.

Acknowledgments

Authorship F.M and B.R. conceived and designed the study; N.S. calculated the DII and drafted the manuscript; N.S performed the data analysis. J.R.H., F.M., and B.R. provided suggestions and critically revised the manuscript. All the authors have read and approved the final version of the manuscript.

Disclosure Statement

Dr. James R. Hébert owns controlling interest in Connecting Health Innovations LLC (CHI), a company planning to license the right to his invention of the dietary inflammatory index (DII) from the University of South Carolina in order to develop computer and smart phone applications for patient counseling and dietary intervention in clinical settings. Dr. Nitin Shivappa is an employee of CHI. The subject matter of this paper will have no direct bearing on the work of CHI, nor has any CHI-related activity exerted any influence on this project.

Additional information

Funding

Drs. Shivappa and Hébert were supported by grant number R44DK103377 from the United States National Institute of Diabetes and Digestive and Kidney Diseases.