Modulating the Skin Microbiome to Prevent Radiation Dermatitis in Breast Cancer

Inclusion Criteria: * Age ≥18 and \<70 years, with pathologically confirmed breast cancer; * TNM stage T1-3N1-3M0 or T3-4N0M0; * Underwent mastectomy with or without implant reconstruction; ④ Medically fit for adjuvant radiotherapy (i.e., in good general condition to tolerate expected side effects such as fatigue, nausea, or vomiting); ⑤ No concurrent use of other skincare products throughout the study period; * Voluntary participation with signed informed consent, agreeing to comply with investigator-directed use of the trial product. Exclusion Criteria: * Prior history of radiotherapy; * Severe systemic diseases (e.g., significant cardiac, hepatic, or renal dysfunction; immunocompromising conditions such as lymphoma, acquired immunodeficiency syndrome \[AIDS\], or Wiskott-Aldrich syndrome) or history of other malignancies; ③ Skin reactions due to systemic therapies (e.g., chemotherapy, immunotherapy) or active dermatologic conditions in the treatment area; * Known hypersensitivity to the natural weak-acid macromolecular/small molecular repair cream or any of its components; ⑤ Current participation in other clinical trials or participation within the past 3 months, or judged by investigators to have poor compliance that would prevent completion of the study.