Abstract
Malignant tumors of the urinary system, including prostate, bladder, and renal cell cancers, pose a significant global health burden. While socioeconomic disparities (SES) are known to influence cancer risk, their causal relationship with urinary system tumors remains inconsistent and underexplored. This study employs Mendelian randomization (MR) to investigate the causal effects of SES indicators - education level and family income - on the risk of these malignancies. Utilizing genome-wide association study summary data from European-ancestry populations, we selected 280 single nucleotide polymorphisms for education (n = 11,31,881) and 30 single nucleotide polymorphisms for family income (n = 3,97,751) as instrumental variables. Inverse variance weighting served as the primary analysis, complemented by sensitivity analyses (MR-Egger, weighted median, MR-PRESSO, and leave-one-out) to assess pleiotropy and robustness. Genetic predisposition to higher education (per 4.2 years) was associated with a 17% increased risk of prostate cancer (odds ratio [OR] 1.17; 95% confidence interval: 1.04-1.31; P < .01). Similarly, higher family income elevated prostate cancer risk by 32% (OR 1.32; 95% confidence interval: 1.02-1.70; P = .033). No causal associations were observed between SES and bladder cancer (education: OR 1.09, P = .59; income: OR 1.08, P = .82) or renal cell cancer (education: OR 1.19, P = .21; income: OR 1.01, P = .98). Sensitivity analyses confirmed the reliability of these estimates. This MR study provides robust evidence that higher SES is causally linked to increased prostate cancer risk, likely mediated by screening access and lifestyle factors. The null associations for bladder and renal cell cancers underscore the organ-specific nature of socioeconomic influences. These findings advocate for SES-stratified screening programs and targeted prevention strategies to mitigate disparities in cancer risk.