In breast cancer, optimal locoregional treatment allows high local control rates and impact long-term survival. The Early Breast Cancer Trialists Collaborative Group (EBCTCG) meta-analysis data showed that radiation therapy (RT) can decrease the risk of breast cancer death at 15 years. In the adjuvant setting, whole breast RT remains the standard of care. Adjuvant systemic therapies, RT indications, techniques and volumes are determined according to the known standard prognosis factors such as age, tumor size and location, nodal involvement, grade, hormone receptors status, proliferative index and lymphovascular invasion. One of the future challenges in breast cancer management is to determine new prognosis and predictive factors that could help to define the subgroups of patients, who will either really benefit from new treatment strategies or particular RT techniques, or for those for whom aggressive local therapeutic option is not needed, as their prognosis is mainly related to an early risk of metastatic diffusion. In the new era of fine biological diagnosis, a better understanding of tumor biology allows a significant development of targeted therapies. Adjuvant strategies including locoregional RT have to be based on the tailored treatment concept. These strategies have to take into account not only the patients profiles regarding the well-established parameters, but also the tumor biology, the new breast cancer subtype classification and gene profiles.