Carcinoma in situ of the breast requires total mastectomy, and some people can also undergo breast-conserving treatment, such as those with tumors less than three centimeters, no peripheral invasion and axillary lymph nodes, and those who have high demands on aesthetics. Carcinoma in situ refers to tumors that do not break through the basement membrane and are only confined to the epithelial mucosa layer, including intraductal carcinoma in situ and lobular carcinoma in situ. Total mastectomy is needed for carcinoma in situ, while breast-conserving treatment is also available for some people, depending on the age of the patient, the condition of the tumor itself and the needs of the patient. Radical mastectomy: for those who are older, with high tumor malignancy and no appearance requirement, radical mastectomy is needed to reduce the risk of recurrence and metastasis, and clinical cure can be achieved without adjuvant radiotherapy after surgery. 2. Breast-conserving surgery: people between 30 and 60 years old, with tumor less than three centimeters, without peripheral invasion and axillary lymph nodes, and with high aesthetic requirements can undergo breast-conserving surgery to treat the local tumor. After local tumor resection, adjuvant chemotherapy is needed to control the tumor, and a clinical cure can be achieved. Early detection, early diagnosis and early treatment of carcinoma in situ can lead to excellent prognosis, and regular checkups should be conducted in regular medical institutions.