Do I have to take radiotherapy after breast conservation? 1.After breast conservation, whole breast radiotherapy is recommended, which can reduce the local recurrence rate by about 2/3, while tumor bed dosing can further improve the local control rate, and the benefit of tumor bed dosing is more significant for patients under 60 years of age. 2. Patients aged 70 years and above, with stage I pathology, positive hormone receptors and negative cut margins can be considered for endocrine therapy alone and not radiotherapy, given their low absolute recurrence rate and slow regression of adverse effects such as breast edema and pain after whole-breast radiotherapy (according to the results of CALGB9343). Patients 65 years and older with hormone receptor-positive masses up to 3 cm in maximum diameter and who can receive standard endocrine therapy may also be considered for remission of postoperative radiotherapy (according to the results of the PRIME II study). When to start radiotherapy after breast conservation? 1. Postoperative radiotherapy is recommended within 8 weeks after surgery for patients who do not require chemotherapy. (Because of the dynamic changes in the volume of the operative cavity in the early postoperative period, especially in patients containing an operative cavity hematoma, it is not recommended to start radiotherapy within 4 weeks after surgery.) 2.Patients who need chemotherapy should be started within 2 to 4 weeks after the last chemotherapy. 3.Endocrine therapy and radiotherapy can be started simultaneously or after radiotherapy. 4.Patients with targeted therapy (trastuzumab) can be treated simultaneously with radiotherapy as long as their heart function is normal before radiotherapy. The target area of radiotherapy after breast-conserving surgery 1. Patients with axillary lymph node clearance or negative sentinel lymph nodes need only include the affected breast. For patients with metastases after axillary lymph node dissection, the target area should include not only the affected breast but also the supraclavicular and infraclavicular lymphatic drainage areas. 3, Patients with only micrometastases or one to two macro-metastases in the anterior sentinel lymph nodes without axillary dissection can be considered for high or conventional breast tangential fields. 4.Patients with more than 2 macro-metastases in the anterior sentinel lymph nodes without axillary lymph node dissection should be irradiated in the axilla and supraclavicular and infraclavicular regions on the basis of whole breast irradiation. 5.The indications for radiotherapy in the internal breast area need to be strictly controlled, and the volume and dose of cardiac irradiation should be reduced as much as possible in patients on the left side.