1. FFPE samples with tumor content \<20%, and inability to enrich tumor regions through cutting.

2. Insufficient extracted nucleic acid quantity or severe degradation preventing further experiments.

3. Failure in RT-PCR amplification of housekeeping genes.

4. Multiple primary breast cancers or a history of ipsilateral or contralateral breast cancer.

5. Disease progression unrelated to breast cancer.

6. Lack of prior signed consent for retrospective scientific research or exemption from informed consent.

Miti-gene Recurrence Score in HR+/HER2- Chinese Breast Cancer Patients