Association between Inflammatory Potential of Diet and Bladder Cancer Risk: Results of 3 United States Prospective Cohort Studies

Purpose: Inflammatory reaction has been linked to bladder cancer. Diet, which drives systemic inflammation, may be considered a modifiable risk factor for bladder cancer. We examined the association of diet with pro-inflammatory potential and bladder cancer risk using the novel EDIP (empirical dietary inflammatory pattern) score comprising predefined food groups determining a pattern most predictive of plasma inflammatory markers. Materials and Methods: We followed a total of 172,802 women in the NHS (Nurses' Health Study) from 1984 to 2012 and the NHS II from 1991 to 2013 as well as 45,272 men in the HPFS (Health Professionals Follow-Up Study) from 1986 to 2012. Multivariable adjusted Cox regression models were used to estimate the RR and 95% CI of bladder cancer across EDIP score quintiles. We performed inverse variance weighted meta-analysis to pool estimates across cohorts stratified by smoking status. Results: During 4,872,188 person-years of observation 1,042 incident bladder cancer cases were identified. Overall, high EDIP scores reflecting dietary patterns with pro-inflammatory potential were not associated with a higher risk of bladder cancer (quintile 5 vs 1 pooled multivariable adjusted RR 0.92, 95% CI 0.75-1.12, p(trend) = 0.67). Results were consistent across individual cohorts (quintile 5 vs 1 in the NHS RR 1.04, 95% CI 0.78-1.37, p(trend) = 0.71; in the NHS II RR 1.44, 95% CI 0.53-3.91, p(trend) = 0.13; and in the HPFS RR 0.74, 95% CI 0.55-1.01, p(trend) = 0.11). Results were similar regardless of smoking status. Conclusions: We observed no association between diets with pro-inflammatory potential and bladder cancer risk. Although additional studies are needed to explore other nutritional pathways with the potential for bladder cancer prevention, our results suggest that diets associated with inflammation are not associated with bladder cancer risk.