The local recurrence rate, immediate and delayed toxicity, the radiation safety and quality assurance data suggest that permanent breast seed implant (PBSI) is a safe and acceptable option of accelerated partial breast irradiation, capable of delivering the right amount of dose in the right location for selected early stage breast cancer. However, those results have been obtained mainly from a single institution, with 4 patients treated in another center. Further research is still needed to evaluate its safety in a multi-center setting and also to detect serious adverse events when a larger number of patients are treated by a larger group of practitioners. Since brachytherapy is operator dependent, a registry represents a unique opportunity to ensure the appropriate training of radiation oncologist and to capture capturing long terms outcomes.