Compared to HT non-users, current users of HT had the highest risk of luminal A (HR 1.97, 95% CI 1.86–2.09) followed by luminal B HER2 negative (HR 1.35, 95% CI 1.29–1.41) and luminal B HER2-positive BC (HR 1.28, 95% CI 1.15–1.43), however current HT users were also at an increased risk of triple-negative BC (HR 1.14, 95% CI 1.02–1.28; Pheterogeneity < 0.001; Table 4). This evidence concerns the gene ERBB2 and breast cancer.