While there are existing clinical trials which have examined the duration of treatment with trastuzumab for breast cancer, there have not been any studies into whether we should continue adjuvant treatment in HER2-positive patients beginning to receive dual blockade neoadjuvant therapy. Fatima Cardoso, MD, from the Champalimaud Clinical Cancer Centre, Lisbon, Portugal speaks to us at the 2017 European Society for Medical Oncology (ESMO) conference held in Madrid, Spain, discussing why this is the case and explaining why the question may be difficult to answer.