Studies investigating the association of food and nutrient consumption with the risk of urothelial cell carcinoma (UCC) have produced mixed results. We used three common dietary scores, the Mediterranean Diet Score (MDS), the Alternate Healthy Eating Index 2010 (AHEI-2010) and the Dietary Inflammatory Index (DII) to assess the evidence of an association between diet and the risk of UCC. Over a median follow-up time of 21.3 years, 379 incident UCC cases were diagnosed. Dietary scores were calculated using data from a 121-item food frequency questionnaire administered at baseline. We used Cox models to compute hazard ratios (HR) for the association between dietary scores (per one standard deviation) and UCC risk. In order to reflect overall adherence to a healthy diet, a metascore was constructed by summing the quintiles of each of the three scores. None of the dietary scores was associated with the risk of UCC overall. A healthier diet was found to be inversely associated with the risk of invasive (MDS: HR = 0.86, 95% CI: 0.74–1.00, metascore: HR = 0.84, 95% CI: 0.71–0.98), but not superficial disease (heterogeneity between subtypes p = 0.04 and p = 0.03, respectively). Results were consistent but weaker for the DII and the AHEI-2010. We found some evidence of effect modification by smoking, in particular for the metascore (Current: HR = 0.77, 95% CI: 0.58–1.01, Former: HR = 0.77, 95% CI: 0.64–0.92, Never: HR = 1.01, 95% CI: 0.81–1.26, p for heterogeneity = 0.05). A healthy diet may be protective against the risk of invasive, but not superficial, UCC. Promoting healthy dietary habits may help lower the risk of invasive UCC, especially for current and former smokers.What's new?
When components of the food we eat interact with the lining of the urethra on their way out, they can influence urothelial cell carcinoma. Various studies have tried to quantify the impact of individual nutrients on UCC risk; this study instead focused on the diet as a whole. Each person's dietary pattern received a score on three separate scales that reflect different philosophies of healthy eating, but the scores did not correlate with overall urothelial cell cancer risk. The authors did find that people with a healthier diet had a lower risk of invasive cancers, and healthier eating especially benefitted smokers.