The MR analysis results, as depicted in Fig 2 (HER2-positive) and Fig 3 (HER2-negative), indicated a suggestive association between genetically predicted IL-5 (IVW-OR: 1.18, 95% CI: 1.04–1.35, P = 0.012), IL-7 (IVW-OR: 1.11, 95% CI: 1.01–1.22, P = 0.037), and IL-16 (IVW-OR: 1.13, 95% CI: 1.02–1.25, P = 0.025) with an increased risk of HER2-positive breast cancer. Here, IL16 is linked to breast cancer.