Matteo Lambertini, MD from Institut Jules Bordet, Brussels, Belgium talks to us from the 2017 European Society for Medical Oncology (ESMO) conference in Madrid, Spain to discuss the ALTTO study (NCT00490139). This was a Phase III, randomized trial to compare the efficacy of the anti-HER2 agents lapatinib and trastuzumab, either alone or in combination, in the treatment of breast cancer patients. Dr Lambertini explains how the trial was discussed at this year’s ESMO meeting, and tells us the main take-home messages.