| Objective To analyze the causal relationship between breast cancer (BC) and osteoporosis (OP) using Mendelian randomization (MR). Methods Using publicly available genome-wide association study datasets (GWAS), with BC as the exposure factor and OP as the outcome, we conducted inverse variance weighting (IVW), weighted median method (WME), and MR-Egger analyses to examine the causal relationship between BC and OP, with IVW as the primary analysis method. Heterogeneity test, pleiotropy test, and sensitivity analyses were used to evaluate the robustness of the study results. Results The IVW analysis indicated that BC might be a risk factor for OP (OR=1.09, 95% CI: 1.03-1.16, P<0.05). Furthermore, heterogeneity test, pleiotropy test, and sensitivity analyses did not observe any horizontal pleiotropy or heterogeneity, suggesting that the study results were robust and reliable. Conclusion There may be a significant potential causal relationship between BC and OP, since BC possibly increases the risk of developing OP. This provides new clues for studying the biological mechanisms of OP and its early prevention and treatment, as well as a new direction for evidence-based medical research. |