The association between systemic glucocorticoids and breast cancer risk were consistent across ER status (Phomogeneity ≥ 0.22, Table 3), tumor stage (Phomogeneity ≥ 0.22, Table 4) and age at index date (Phomogeneity ≥ 0.11, Supplementary Table S1). Here, ESR1 is linked to breast cancer.