Purpose: Previous studies have provided limited evidence for an adverse effect of high glycemic index (GI) and glycemic load (GL) on bladder cancer risk. This study aimed to examine the association between GI, GL and bladder cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Screening Trial.
Methods: GI and GL scores were computed among 101,721 participants in the PLCO study. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox regression model adjusting for confounders.
Results: After a median of 12.5 years of follow-up, 776 incident bladder cancer cases occurred. There was no significant association between bladder cancer risk and GI (HRQ5vsQ1 = 1.18, 95% CI 0.94-1.48, p for trend = 0.177) or GL (HRQ5vsQ1 = 0.92, 95% CI 0.65-1.30, p for trend = 0.826). The associations did not differ by continuous analyses. Spline regression plots revealed a lower risk of bladder cancer with higher GI or GL, but the difference was not statistically significant. There was no statistical evidence for nonlinearity (P for nonlinearity > 0.05).
Conclusion: In summary, analysis of the PLCO cohort did not provide evidence that higher GI or GL diets were associated with greater bladder cancer risk.
Keywords: Bladder cancer; Cohort; Glycemic index; Glycemic load; PLCO.