According to the latest data from the World Health Organization's International Agency for Research on Cancer (IARC) for 2020, breast cancer has been the most prevalent cancer with 2.26 million new cases. Among Chinese breast cancer patients, approximately 60% are hormone receptor (HR) positive, and 80% have early-stage breast cancer. For HR-positive, human epidermal growth factor receptor-2 (HER2) negative breast cancer patients, the first peak of recurrence is about 2-3 years after surgery, especially for patients with high-risk clinical and/or pathological features. Therefore, adjuvant therapy is essential to reduce recurrence during this period.

Capecitabine is an anti-metabolite fluoropyrimidine deoxynucleoside carbamate that can be converted to fluorouracil (5-Fu) in vivo. Studies have shown that patients with HR-positive HER2-negative breast cancer with high-risk factors may benefit from postoperative adjuvant capecitabine therapy as well as patients with triple-negative breast cancer. Therefore, we assumed that additional capecitabine may reduce the reccurence of breast cancer in patients with high-risk factors.

This trial is an open, single-arm clinical trial designed to investigate the effect of additional adjuvant capecitabine therapy on recurrence and survival in HR-positive HER2-negative breast cancer patients with high-risk factors.

Inclusion Criteria:

• Female, age 18-70 years.
• Completed radical breast cancer surgery with confirmed pathology suggested primary invasive breast adenocarcinoma, ER and/or PR positive (defined as positive cells >1%) and HER2 negative (defined as HER2 immunohistochemistry 2+ or less and FISH negative).
• Definition of high-risk factors: 4 or more positive axillary lymph nodes; 1-3 positive axillary lymph nodes with primary tumor ≥ 5 cm or histologic grade 3 or ki67 ≥ 20%; or residual lesions despite neoadjuvant chemotherapy.
• No prior treatment for present breast cancer onset.
• ECOG physical status score 0 to 1
• Hematological examination before treatment should meet: white blood cell count (WBC) ≥ 4.0×10^9/L, neutrophil count (ANC) ≥ 1.5×10^9/L, platelet count (PLT) ≥ 100×10^9/L; hemoglobin (Hb) ≥ 90g/L; AST (sGOT), ALT (sGPT) ≤ 1.5 times the normal value upper limit, creatinine ≤ 1.5 times the upper limit of normal value, total bilirubin ≤ 1.5 times the upper limit of normal value.
• No serious impairment of heart, liver, kidney and other important organ functions.

Exclusion Criteria:

• Unwilling or unable to use an acceptable method of contraception for up to and including 8 weeks after the final dose of the test drug.
• Women during pregnancy and breastfeeding after pregnancy.
• Women with proven distant metastases of breast cancer.
• Patients with proven sensory or motor nerve disease.
• Definite cardiovascular disease, severe co-morbidity or active infection, including known HIV infection.
• Patients who need long-term anticoagulant drugs for cardiovascular or thrombotic diseases.
• History of other tumors.
• Allergic to the study drug or its excipients, etc.