PERSEPHONE: are we ready to de-escalate adjuvant trastuzumab for HER2-positive breast cancer?

Shorter duration trials—design & definition of non-inferiority. Legend: 1. R randomization, DFS disease-free survival, HR Hazard Ratio, CI confidence interval, FEC 5-fluorouracil, epiribucin, cyclophosphamide, AC anthracyline, cyclophosphamide, EC epirubicin, cyclophosphamide. Trastuzumab could be combined with or sequential with chemotherapy; 2. Patients could be randomised at any point in time up to the 6th month of treatment. 3. The HRs are calculated with shorter arm relative to longer arm, hence the upper bound of confidence interval HR margin greater than 1.00 indicates the maximum increase in relative risk of a DFS event that would be tolerated in order to declare the shorter duration treatment as non-inferio