A cause-effect relationship between uterine diseases and breast cancer: A bidirectional Mendelian randomization study

To explore the cause-effect relationship between uterine diseases (UDs) and breast cancer (BC) and underlying mechanism of the cause-effect relationship, enhance understanding of the association between BC and UDs.

A two-sample bidirectional Mendelian randomization (MR) analysis was conducted. We obtained summary statistics data from GWAS for BC, endometriosis, endometrial cancer (EC), uterine leiomyoma (UL), uterine polyps (UP), and cervical cancer (CC). Independent SNPs were selected as instrumental variables (IVs) for each disease. The inverse variance weighted (IVW) method was primary used for estimating the causal association between UDs and BC. To further evaluate the consistency and dependability of the results, we also utilized the weighted median, weighted mode, simple mode, and MR-Egger methods, along with sensitivity analyses. Furthermore, a supplementary analysis focusing on the variants linked to BC and UDs was conducted. This involved identifying corresponding genes and subsequently performing KEGG/GO analyses to investigate potential molecular mechanisms.

The results indicated significant associations between genetic susceptibility to endometriosis, EC, and UL with BC risk. The odds ratios (ORs) were as follows: endometriosis at 0.963 (95 % CI, 0.942-0.984; p = 7.11e-5), EC at 1.056 (95 % CI, 1.033-1.081; p = 2.39e-6), and UL at 1.027 (95 % CI, 1.006-1.048; p = 0.010). Conversely, the predisposition to BC inferred from genetic factors was markedly correlated with an elevated risk of EC indicated by an OR of 1.066 (95 % CI, 1.019-1.116; p = 0.006), and was correlated with UP risk (OR, 1.001,95 % CI, 1.000-1.002; p = 0.001).Sensitivity analyses provided weak evidence for these effects, suggesting that the study's outcomes are consistent and trustworthy. Further analysis of the genetic variants associated with BC, and these related genes are enriched in Cellular senescence, GnRH secretion, Phosphatidylinositol signaling system, and so on.

This study corroborates the existence of a reciprocal causal relationship between BC and EC, as well as highlighting the substantial correlations between a genetic susceptibility to UL and endometriosis with BC. BC may exert their influence on EC and UP through Cellular senescence, GnRH secretion, and other pathways. These discoveries offer fresh perspectives on the genetic pathogenesis of BC and UDs, and can guide future experimental studies. Additionally, they lay down a groundwork for the development of tailored preventative and therapeutic strategies moving forward.