During ESMO 2018 an entire presidential session was dedicated to breast cancer. In addition to exciting immuno-oncology data in the treatment of triple negative breast cancer (TNBC), this session featured the presentation of the overall survival (OS) data of the phase III PALOMA-3 trial, evaluating the alpha-specific PI3K-inhibitor alpelisib in PI3KCA-mutant advanced breast cancer, and results of a clinical trial demonstrating improved outcomes when adding a histone deacetylase (HDAC) inhibitor to exemestane in hormone-receptor positive advanced breast cancer. In early breast cancer it was further demonstrated that non-compliance with adjuvant endocrine treatment is an under-appreciated and under-reported problem. In addition, the HOBOE-2 adds to the evidence that adjuvant bisphosphonates also improve the disease-free survival (DFS) in premenopausal luminal breast cancer patients who have received ovarian function suppression combined with an aromatase inhibitor. Finally, a subgroup analysis of the ShortHER trial suggests that for low- and intermediate risk cancer HER2-positive early breast cancer, 9 weeks of trastuzumab might be non-inferior to the standard 1-year treatment duration. However, the interpretation of this trial is challenging and as such, one year of trastuzumab should remain the standard for now.
