This study aims to evaluate the efficacy and safety of capecitabine as the only adjuvant chemotherapy drug in patients with low-risk early triple-negative breast cancer who have received adequate local treatment. Patients meeting the inclusion criteria will receive capecitabine metronomic therapy for one year.

This study aims to evaluate the efficacy and safety of capecitabine as the only adjuvant chemotherapy drug in patients with low-risk T1N0M0 early triple-negative breast cancer who have received adequate local treatment. Patients meeting the inclusion criteria will receive capecitabine metronomic therapy for one year. The low-risk population defined in this study includes the IM subtype with abundant stromal tumor-infiltrating lymphocytes, or the LAR subtype with low ki-67 proliferation, or elderly patients.

Inclusion Criteria:

1. Male and female patients aged ≥18 years;
2. Pathological confirmed of stage I breast cancer: histologically confirmed that the longest diameter of invasive cancer is no more than 2cm and the lymph node is negative (N0);
3. Histologically documented TNBC after early breast cancer surgery (absence of HER2, ER, and PR expression)
4. Patients who have undergone standard and adequate surgical treatment;
5. Has adequate organ function meeting the following criteria: (1) adequate bone marrow function: hemoglobin ≥ 90 g/L (no blood transfusion within 14 days); absolute neutrophil count ≥ 1.5 x 109 /L; platelet count ≥ 100 * 109 /L; (2)adequate liver and kidney function: Alanine Aminotransferase (ALT) ≤ 3×upper limit of normal (ULN), Aspartate Aminotransferase (AST) ≤ 3×ULN, Total Bilirubin (TBIL)≤ 1.5×ULN, serum creatinine ≤ 1×ULN#and with endogenous creatinine clearance rate of >50 ml/min (Cockcroft-Gault formula);
6. No evidence of metastasis in clinical or imaging examinations before surgery, that is, M0;
7. ECOG score of 0 or 1;
8. Meeting one of the low-risk criteria defined in this study: a) IM subtype, that is, the proportion of stromal tumor-infiltrating lymphocytes is high or CD8 is high; b) LAR subtype and ki-67 less than 20%; c) Age ≥ 70 years.

8)The patient voluntarily joined the study, signed the informed consent form, had good compliance, and cooperated with the follow-up.

Exclusion Criteria:

1. Has received neoadjuvant therapy (include chemotherapy, targeted therapy, radiotherapy or endocrine therapy;
2. Has previous history of additional malignancy, with the exception of adequately treated basal cell carcinoma and cervical carcinoma in situ;
3. Has metastic (Stage 4) breast cancer;
4. Pregnant or breast feeding women, or people of childbearing age who cannot practice effective contraceptives;
5. Patients participating in other clinical trials at the same time;
6. Has severe organ dysfunction (cardiopulmonary liver and kidney) insufficiency, left ventricular ejection fraction (LVEF) < 50% (cardiac ultrasound); severe cardio cerebral vascular disease within the 6 months previous of randomization (such as unstable angina, chronic heart failure, uncontrolled hypertension with blood pressure>150/90mmHg, myocardial infarction, or cerebral blood vessel); diabetic patients with poor blood glucose control; patients with severe hypertension; Has severe or uncontrolled infection; 7) Has a history of psychotropic substance abuse and were unable to abandon drug habits, or those with history of mental disorders; 8)The researchers considered patients to be unsuitable for the study. 9)Has bilateral breast cancer