Successful ventilator weaning by trastuzumab in a HER2-positive breast cancer patient with multiple lung metastases

We report a case of breast cancer with severe respiratory dysfunction due to multiple lung metastases, which was recovered by treatment with weekly trastuzumab administration. A 47-year-old woman with breast cancer had received a folk remedy from a general practitioner for 4 years. However, she was delivered to a hospital because of severe dyspnea, and intubation was found to be needed and performed. She was diagnosed with left breast cancer with skin and pleural wall invasion, and multiple lung metastases. Pathological examination showed invasive ductal carcinoma which was ER-postive, PgR-negative, and HER2-postive. After transfer to our hospital, treatment with trastuzumab (4 mg/kg/weekly for the first course, and 2 mg/kg/weekly thereafter) was administered. Respiratory function improved gradually, and ventilator weaning was successful at 53 days after trastuzumab administration. CT examination also showed a remarkable reduction of lung and lymph node metastases and pleural effusion. She was discharged from our hospital 80 days after treatment, and her treatment with trastuzumab and capecitabine has been ongoing at an outpatient clinic.