Breast cancer lump 4cm can be operated directly without neoadjuvant therapy. The treatment of breast cancer is a comprehensive treatment mainly based on surgery, which includes radiotherapy and drug treatment in addition to surgery. For a 4cm breast cancer lump, different hospitals have different treatment methods, and some hospitals will give priority to preoperative neoadjuvant therapy to reduce the size of the tumor, and then perform surgical resection. However, in this case, it will be accompanied by lymph node metastasis or the patient’s willingness to conserve breasts. If the patient does not want to preserve breasts and the axillary lymph nodes are not enlarged or minimally infiltrated, total mastectomy can be performed first, and it is difficult to perform breast-conserving surgery at this time. Patients are advised to go to a regular hospital as soon as possible, and the choice of treatment should be made under the guidance of oncologists or breast surgeons.