Study on Recurrent Breast Cancer and Repeated Radiation Therapy

Inclusion Criteria: * The patient has a diagnosed breast cancer or tumor area in the breast with a maximum diameter of 3 cm, where a previous breast-conserving surgery has been performed (either invasive breast cancer or carcinoma in situ, DCIS). The patient has only a local recurrence, and imaging studies show no suspicion of metastases outside the breast (preoperative staging N0M0). At least 3 years have passed since the completion of prior radiation therapy. The new breast cancer can be technically treated with another breast-conserving surgery using a technique that does not require tissue transfer from areas opposite the removed tumor to restore the shape of the breast. The patient is at least 55 years old at the time of surgery. The patient is willing to participate in the study. The patient is capable of providing informed consent. Exclusion Criteria: * A booster dose, also known as a "boost," was administered during prior radiation therapy. Preoperative assessments suggest multifocal breast cancer, with the tumor area to be removed exceeding 3 cm. The planned radiation therapy per the study protocol cannot be administered due to factors such as shoulder joint stiffness, a pacemaker located in the radiation field, or a skin condition (e.g., scleroderma). The patient is unable to provide informed consent or is unwilling to participate in the study. Metastases outside the breast (e.g., axillary or distant metastases) are present.