[A Case of Recurrent Breast Cancer with Contralateral Axillary Node Recurrence Cured after Mastectomy for Ipsilateral Breast Tumor Recurrence].

A 65-year-old woman was treated with breast-conserving therapy for dissection of the left breast and axillary lymph nodes. Histopathological diagnosis was invasive breast cancer(scirrhous), T1cN2M0, stageⅡB, ER+/PgR+/HER2-. Approximately 4 years later, a mass found in her left breast was confirmed to be ipsilateral breast tumor recurrence(IBTR). Left mastectomy was performed because no clear metastasis was found on whole-body examination. Histopathological diagnosis was invasive breast cancer(solid-tubular), ER-/PgR-/HER2-. IBTR was of a different type, compared to the primary breast cancer. In the follow-up period, multiple axillary lymph node metastases were found in the right axilla. Histopathologically, 20 lymph node metastases were found, and ER-/PgR-/HER2-breast cancer-related lymph node recurrence was diagnosed. Postoperative adjuvant chemotherapy(PTX, TS-1)was administered. In the 10 years following IBTR, there has been no recurrence, and it is thought to be completely cured. Usually, contralateral axillary lymph node recurrence is treated the same way as distant metastases because they are extra-regional lymph nodes; however, this strategy is not applicable to IBTR. When surgery is performed for IBTR, the contralateral axillary lymph node may become a new sentinel lymph node, and thus, sufficient examination and accurate risk assessment may be necessary before surgery for local control.