Can maintenance trastuzumab be stopped in patients with HER2-positive metastatic breast cancer?

Trastuzumab has significantly improved the median survival of patients with HER2-positive breast cancer. In metastatic disease, maintenance trastuzumab is usually given after tumour response has been achieved with the combination of chemotherapy and trastuzumab, with the aim of prolonging time to disease progression. We report a case where a durable complete response (CR) was achieved without maintenance trastuzumab. In the absence of consensus guidelines, it is difficult to recommend which HER2-positive patients with metastatic breast cancer after CR will benefit from withdrawing maintenance trastuzumab therapy and when this could be considered.