Exceptional Responses to Standard Therapy in a Patient with Metastatic HER2-Positive Breast Cancer.

Patients with metastatic breast cancer involving the liver and brain often have short overall survival. Here, we report a case of de novo metastatic breast cancer with multiple liver metastases at initial diagnosis in February 2011 in a 35-year-old Caucasian female patient. The histology was poorly differentiated invasive ductal carcinoma (estrogen and progesterone receptor negative, HER2 positive) and the patient was negative for germline BRCA 1 and 2 mutations. Systemic therapy with trastuzumab and docetaxel was given for six months and then switched to trastuzumab only because of peripheral neuropathy. At that time, the patient was in complete clinical remission. She developed brain metastases in September 2012 and received whole-brain radiotherapy, which resulted in complete remission. While on continued trastuzumab, the primary tumor in the breast recurred in May 2016. A mastectomy was performed and afterwards systemic therapy was intensified (trastuzumab, pertuzumab, paclitaxel). At the last follow-up (March 06, 2017) no further recurrence was detected. This case illustrates that standard HER2-directed treatment might provide long-term disease control also in selected patients with unfavorable patterns of spread. The beneficial effect of whole-brain radiotherapy is not necessarily limited to symptom palliation.