A Prospective Study of Preoperative Tumor-bed Boost Followed by Oncoplastic Surgery and Adjuvant Whole Breast Radiotherapy for Early Stage Breast Cancer (BIRKIN)

Inclusion Criteria: 1. Patients diagnosed with invasive breast cancer; 2. cN0 based on clinical physical examination combined with at least two imaging tests, or axillary fine-needle biopsy proved pN0; 3. Patients who plan to receive breast-conserving surgery or breast-conserving oncoplastic surgery; 4. No distant metastasis; 5. The primary tumour\> 5mm from the skin, without invasion of the ribs or intercostal muscles; 6. No neoadjuvant systemic therapy; 7. Patients who can tolerate MRI; 8. Life expectancy ≥5 years; 9. Organ function is fine (Hemoglobin ≥100g/L, leukocyte ≥2×109/L, neutrophil ≥1×109/L, platelet ≥80×109/L; Creatinine 1.5 mg/dl or less; Alanine aminotransferase/aspartate aminotransferase ≤2.5×UNL.); 10. Patients are willing to cooperate to follow up; 11. Patients should sign the informed consent; 12. Women of childbearing age need effective contraception. Exclusion Criteria: 1. Concurrent active connective tissue disease; 2. Patients who had radiotherapy to the ipsilateral breast or adjacent areas before; 3. Other malignancies, which affect pateint life expectancy (except adequately treated basal cell carcinoma of the skin, carcinoma in situ of the cervix, superficial bladder neoplasms (no more than T1)); 4. Severe comorbidities or active disease (Poorly controlled heart disease: New York Classification of Cardiac Function ≥ Grade 2, active coronary heart disease, unstable angina pectoris, arrhythmia requiring medical treatment/persistent refractory hypertension; Myocardial infarction, stroke within six months; Poorly controlled diabetes persists. Fasting blood glucose ≥ 10mmol/L, 2 hours postprandial blood glucose ≥ 13 mmol/L. Poorly controlled psychosis develops or worsens within six months; Active infection; Positive for antibodies to HIV).