Randomized trials demonstrated similar overall survival between mastectomy and breast-conservative surgery followed by adjuvant radiation therapy. Breast-conservative surgery, with adjuvant radiation therapy, with or without neoadjuvant systemic therapy has become the standard of care for women with early or locally advanced breast cancer. Nevertheless, certain cardiac, lung or cutaneous toxicities may alter the long-term body image and the quality of life of a limited number of patients who consider having had "overtreatment" or treatment outside the best knowledge of science. In case of low-risk breast cancer, several trials have evaluated the carcinologic outcome in absence of radiation therapy after breast-conservative surgery. Local recurrences increased in case of breast-conservative surgery alone but without impact on overall survival. Multiple debates have emerged in order to select the most appropriate evaluation criteria. Finally, a large consensus has considered that reducing local recurrences is important but with modern technologies and after identifying patients of individual radiosensitivity. Indeed, in case of a low absolute risk of local recurrence, radiation therapy techniques have been developed to allow a focal treatment especially for patients with high risk of developing late effects. This kind of compromise takes into account the reduction risk of local recurrences but also the probability of developing radiation-induced cutaneous sequelae. In the same way, for patients considered at high risk of recurrence, the huge volumes need specific techniques to better cover the targets while protecting the surrounding critic organs such as heart and lung. Intensity-modulated radiation therapy and the local high boost may help to decrease local recurrences of these more extended and aggressive diseases while considering the individual radiosensitivity that paves the way of long-term sequelae. In this article, we detail a personalized approach of breast radiation therapy considering the absolute risk of local recurrences and the probability of radiation-induced toxicity appearance.