The primary end point was invasive breast cancer-free survival (IBCFS), calculated from the sixth year after the initiation of adjuvant endocrine therapy (ET; study baseline), and adjusted through the propensity score (PS) weighting analysis.<h4>Results</h4>A total of 501 patients were included in the analysis: 287 received eET for a median duration of 3.7 years (IQR, 2.3-5.0), including 48% tamoxifen monotherapy and 52% LHRHa plus tamoxifen or aromatase inhibitor. The gene discussed is CYP19A1; the disease is invasive breast carcinoma.