Abstract
OBJECTIVES: This study aimed to examine the causal relationships between peripheral immune cell counts and prostate cancer, adhering to Mendelian Randomization reporting guidelines for transparency and reproducibility. METHODS: In this study, bidirectional Mendelian randomization (MR) analysis, which includes MR-Egger, weighted median, weighted mode, and inverse variance weighted (IVW) approaches, was utilized to evaluate the bidirectional causal relationship between peripheral immune cell counts and the risk of PCa. RESULTS: The primary analysis using the IVW method suggests a potential causal association between basophil counts and the risk of prostate cancer (PCa), with an odds ratio (OR) of 1.111 and a 95% confidence interval (CI) of 1.011-1.222 (P = 0.028). Conversely, non-causal associations have been observed between other peripheral immune cell types, such as white blood cells, neutrophils, lymphocytes, eosinophils, or monocytes, and the incidence of PCa (P values > 0.05). Furthermore, although reverse analysis indicated a causal link between PCa and the counts of leukocytes and neutrophils (OR = 1.013; 95% CI = 1.002-1.225; P = 0.018 and OR = 1.013; 95% CI = 1.002-1.025; P = 0.019), no causal association was detected between PCa and basophil count (P value > 0.050). CONCLUSION: This study suggests a potential bidirectional link between peripheral immune cells and prostate cancer, but inconsistencies in Mendelian Randomization methods mean these findings are preliminary and require further investigation.