The association between diet and bladder cancer risk: a two-sample mendelian randomization

Bladder cancer (BC) is the ninth most common cancer globally, with notable gender and regional differences. Due to the inconclusive impact of diet on BC risk and the inherent biases from observational studies, this research investigates the causal role of dietary patterns (DPs) in BC risk using Two-Sample Mendelian Randomization (TSMR).

Genetic variants were used as instrumental variables (IVs) to analyze 14 food/beverage items and four DPs. Summary-level exposure and outcome data were derived from UK Biobank GWAS (>500,000 participants). The inverse-variance weighted (IVW) method was the primary approach, supported by sensitivity tests including weighted median, MR-Egger regression, and MR-PRESSO.

No causal links were identified between BC risk and 14 specific foods or two DPs (Low-Caloric and Acquired Diet Patterns). However, greater adherence to PC1 (high in whole grains, fruits, and vegetables) was associated with a reduced BC risk (OR: 0.74, 95% CI 0.61-0.89, p < 0.05). In contrast, the Highly Palatable Dietary Pattern (HPDP), rich in processed and high-calorie foods, was linked to a more than twofold increase in BC risk (OR: 2.81, 95% CI 1.43-5.52, p < 0.05). These findings were consistent across sensitivity analyses, with no evidence of pleiotropy or heterogeneity.

Adherence to PC1 may lower BC risk, while HPDP may increase it, emphasizing the relevance of overall dietary habits in BC prevention. Further research in diverse populations is recommended to develop more targeted prevention strategies and better translate findings into practice for improved BC-related public health outcomes.