Safety of Breast-Conserving Surgery for Multifocal or Multicentric Breast Cancer

The objective of this observational study is to evaluate the oncological safety of breast-conserving surgery combined with standard postoperative radiotherapy in adult female patients diagnosed with multifocal or multicentric breast cancer. The main questions it aims to answer are: What is the local recurrence rate and the time distribution of local recurrence after breast-conserving therapy in patients with multifocal or multicentric breast cancer? What independent risk factors are associated with postoperative local recurrence among these patients? There is no separate comparison group in this single-arm prospective cohort study. Participants will: Receive standardized breast-conserving surgery plus routine postoperative radiotherapy and individualized adjuvant therapy in accordance with clinical guidelines; Complete regular clinical follow-up visits, telephone and WeChat follow-ups for at least 3 years after surgery to collect data on surgical complications, tumor recurrence, metastasis and survival status; Fill out standardized questionnaires including Breast-Q, SDS, SAS and EORTC QLQ-C30 to assess postoperative breast satisfaction, psychological status and quality of life.