• The surgical method for breast cancer is determined according to the size and location of the remaining lesions after prior chemotherapy.
• There are many patients who were able to undergo partial resection when confirming the final results of patients who underwent total resection after prior chemotherapy.
• Therefore, we would like to investigate whether it is effective to make decisions based on the results of pre-operative tests after prior chemotherapy.

In a study published by Jennifer F. et al., sensitivity to lesions remaining after prior chemotherapy of breast magnetic resonance imaging was measured as 83%, specificity 47%, PPV 47%, NPV 83%, and accuracy 74%. have.

Most of the preoperative examinations after prior chemotherapy have the most confidence in the results of breast magnetic resonance imaging, but there will be other factors to predict this result as there will be differences in the actual postoperative pathology results. .

After prior chemotherapy, total resection was performed, and cases where partial resection is possible in the postoperative pathologic results are prospectively identified and compared and analyzed.

Inclusion Criteria:

• Breast cancer patients over 20 years of age undergoing surgery at Seoul National University Hospital
• Patients to undergo total mastectomy
• Patients who received neoadjuvant chemotherapy and undergoing total mastectomy were the main subjects, but as a control group, patients who did not receive neoadjuvant chemotherapy but undergoing total mastectomy were included as subjects.

Exclusion Criteria:

• In case of total mastectomy at the request of the patient
• Except for cases where total resection is performed regardless of size because it is a lesion under the areola and is close to the nipple.