ABSTRACT
The current therapeutic strategy in breast cancer rests on standard prognostic factors such as size, histological grade, nodal and hormone receptor status. However, over the last decade, a new form of molecular classification has emerged to complement the classical clinico-pathological staging. Models based on tumour genome have been developped to help predict the risk of relapse, and are currently being evaluated. This improved risk stratification tool would enable the identification of patients who would benefit from systemic as well as local treatments. This paper aims to give an overview of the radiobiological implications in particular of this new classification, by looking at on the one hand, predictors of local relaspe, and on the other hand, the modulation in radiotherapy according to molecular type.