A case of HER2-positive metastatic breast cancer responding to trastuzumab plus gemcitabine combination therapy

A 60-year-old woman was admitted to the hospital with left thigh pain. She had undergone mastectomy and axillary lymph node dissection for right breast cancer (T3N2M0) five years and two months earlier. The pathological diagnosis then was invasive ductal carcinoma with axillaryly mph node metastases. Hormone receptors and HER2 status were negative and positive (3+), respectively. The patient received adjuvant chemotherapy and radiotherapy, but bone metastases appeared 18 months after surgery. Although trastuzumab-combination chemotherapy with taxane and/or capecitabine was given, bone metastases in thoracic vertebra resulted in incomplete paralysis in both legs. She underwent thoraco-lumbar vertebral fixation 10 months before admission. A PET/CT revealed multiple bone metastases in the left femur as well as vertebrae, and CEA rose markedly. She received radiotherapy and trastuzumab monotherapy in addition to bisphosphonate. Temporarily, CEA decreased, but because recurrence nests were recognized in the supraclavicle and mediastinum after the eight-month treatment, trastuzumab monotherapy was followed by trastuzumab plus vinorelbine combined therapy. This regimen markedly reduced CEA after three months, but it rose again over the following three months. As S-1-combined therapy was not effective, trastuzumab+gemcitabine (1 g/week and two weeks on/one week off) combined therapy was started. CEA decreased markedly after 4 cycles, and FDG accumulation in the recurrence region was markedly improved. The adverse event during this treatment was minor, and PS was sufficiently maintained. These results suggest that trastuzumab plus gemcitabine combination therapy is effective for HER2-positive metastatic breast cancer.