[Conversion Therapy for HER2-Positive Metastatic Breast Cancer with Intrathoracic Lymph Node Metastasis].

A 42-year-old woman consulted our hospital with chief complaints of a right breast mass and pain. Based on needle biopsy of the breast tumor, the pathological diagnosis was invasive ductal carcinoma(scirrhous type), which tested positive for estrogen, progesterone, and HER2 receptor. PET-CT(FDG)showed intrathoracic lymph node metastasis. After several tests, she received a diagnosis of cT2N1M1(LYM), Stage Ⅳ breast cancer. She received pertuzumab, trastuzumab, and docetaxel treatments. After chemotherapy, the intrathoracic lymph node and breast tumors were not observed. She underwent mastectomy and axillary lymph node dissection. The pathological diagnosis showed a complete response after surgery. The patient's postoperative course was uneventful; she had received radiotherapy and anti-HER2 therapy. Twenty-three months after the surgery, no recurrence was observed. Herein, we report successful treatment of Stage Ⅳ breast cancer with conversion therapy.