Comparative Evaluation of Efficacy and Safety of Toremifene, Tamoxifen, and Aromatase Inhibitor Plus Ovarian Function Suppression in Hormone Receptor-Positive Early Breast Cancer Among Non-Low-Risk Premenopausal Women: A Real-World Study

Inclusion Criteria:

1. Female, aged 18-60
2. Premenopausal patients with early hormone receptor-positive breast cancer at intermediate to high risk (Low risk is defined as having the following 6 items at the same time: lesion size (pT) in the specimen \<= 2cm; histological grade 1; no vessel carcinoma embolus; ER and/or PR positive; HER2 gene without overexpression or amplification; age \>=35 years old)
3. Completed radical surgery for breast cancer
4. Undergoing postoperative endocrine therapy (toremifene, tamoxifen, aromatase inhibitorI) at least five years at Sun Yat-sen Memorial Hospital of Sun Yat-sen University since 2010
5. Undergoing ovarian function suppression (Oophorectomy, Ovarian irradiation, Gonadotropin-releasing hormone agonist)

Exclusion Criteria:

1. Imaging or pathology suggestive of metastatic breast cancer (chest wall, lung, bone, liver, brain)
2. Patients with a second primary tumor
3. Hepatic insufficiency at baseline
4. Known history of psychotropic substance abuse or drug abuse;