Optimal dose, schedule and tolerability of this drug in the first line setting are unknown in the elderly population. No information on dose modifications in this population is available. Based on the data of eribulin in the first line with higher efficacy in those patients with dose reductions, the SAKK 25/14 trial investigates the reduced starting-dose of eribulin of 1.1mg/m2 for this vulnerable population of elderly patients. Growth factors to maintain a certain dose level of eribulin are not recommended, respecting the international guidelines.