The results revealed a negative causal relationship between triglyceride levels and overall breast cancer risk (odds ratio [OR] = 0.94, confidence interval [CI] = 0.89–0.99, p = 0.011), luminal A breast cancer risk (OR = 0.93, CI = 0.87–0.99, p = 0.014), and human epidermal growth factor receptor 2 (HER2)‐enriched breast cancer risk (OR = 0.84, CI = 0.73–0.96, p = 0.010). This evidence concerns the gene ERBB2 and breast cancer.