Evidence from our IVW analysis revealed that genetically predicted levels of IL-5 [odds ratio (OR): 1.18, 95% confidence interval (CI): 1.04–1.35, P = 0.012], IL-7 (OR: 1.11, 95% CI: 1.01–1.22, P = 0.037), and IL-16 (OR: 1.13, 95% CI: 1.02–1.25, P = 0.025) were associated with an increased risk of HER2-positive breast cancer. This evidence concerns the gene IL16 and breast cancer.