ESR1 and invasive ductal breast carcinoma: Significantly elevated risks for ever EPT use were seen for subtypes defined by ER/PR status (HR for ER+/PR+ = 1.67, 95% CI 1.51–1.85; for ER−/PR− = 1.57, 95% CI 1.24–1.99) (Fig. 2) and by histology (HR for invasive ductal carcinoma (IDC) = 1.53, 95% CI 1.40–1.67; for invasive lobular carcinoma (ILC), HR = 1.45, 95% CI 1.17–1.81; Fig. 3).