Since the end of the sixties, conservative radiosurgical treatment is the standard for unifocal breast cancers < 3 cm. Retrospective and randomised trials confirmed identical survival, but an increased second failure's rate. Impact of this local failure on survival is controversy. Different prognostic factors were identified by the authors. Local extension of the local failure and inflammatory signs, the delay of its apparition and its site (witch could difference true local failure and new tumour) the histologic type of the local failure, the phase S cells rate, the N status, and characteristics of the initial tumour such as the N status, the tumour's size. The surgical treatment of the local failure is classically the salvage mastectomy associated with immediate breast reconstruction, often by cutaneous-muscular flaps. A second conservative treatment could eventually be proposed only if breast size and radiotherapy sequels would permit a second carcinologic and cosmetic surgical treatment: wide local excision and re-irradiation, unifocal tumour < 1 cm preferentially intraductal, well differentiated without lymphovascular embole, without extensive intraductal, second new cancer (in other quadrant than the initial tumor after a long enough delay), efficient and long time survey. RMN with identification of the prognostic criteria would contribute to identify the local failure witch could benefit of an iterative conservative treatment.