To observe and evaluate the clinical efficacy and safety of continuous use of OFS for premenopausal patients with early breast cancer after 5 years use of OFS.

This study is a multicenter, prospective, observational, non randomized controlled, open-label real world study based on hospital medical record system data, aimed at evaluating the benefits of continuing to use OFS after 5 years of use. The retrospective analysis plan includes patient data from September 1, 2023 to September 1, 2026. Join two cohorts: the continued use group and the discontinued use group after 5 years of OFS, respectively.

Inclusion Criteria:

• Diagnosed with early primary breast cancer
• Female aged 18-60 years (including 18 year and 60 year)
• Hormone receptor (HR) positive HER2 negative
• Receive 5 years of OFS treatment
• ECOG score 0-1
• Voluntarily join this study and sign the informed consent form;
• The researcher believes that it can benefit.

Exclusion Criteria:

• The patient is receiving treatment that affects OFS at the same time The patient has received OFS treatment for less than 5 years
• Central nervous system metastases with known obvious symptoms, such as headache, cerebral edema, blurred vision
• Invasive metastases with known obvious symptoms
• Invasive metastases with known obvious symptoms
• Doctors think it is not suitable for inclusion

Women who are diagnosed as early breast cancer and have received 5 years treatment of OFS.