Résumé : The principal mission of the Breast International Group (Big), Transbig, and the Breast European Adjuvant Study Team (Breast), all located at the Jules Bordet Institute in Brussels, is to accelerate and facilitate the initiation and conduct of large and difficult breast cancer clinical trials. This is made possible through the excellent network of research groups, scientists, physicians and many other collaborators deeply committed to academic clinical and translational research. A clear example of this collaboration is the HERA trial (Herceptin Adjuvant trastuzumab in HER2 positive early breast cancer) that contributed to a change of clinical practice and improved the prognosis for this particular patient population. In addition, there is an important new generation of adjuvant trials, for example, Mindact, which is evaluating the use of microarray technology in treatment decision making, and the Altto and Neo-Altto studies, which have just started and are evaluating lapatinib, a small tyrosine kinase molecule given either adjuvantly or neo-adjuvantly, alone, sequentially or in combination with trastuzumab, in patients with HER2 positive early breast cancer. The latter studies, with their strong translational research component, aim to determine which tumour profiles will best benefit from lapatinib as opposed to treatment with trastuzumab alone.