Observational Study of Intra-operative Partial Irradiation of Invasive Ductal Breast Carcinomas With a Good Prognosis

Due to screening, T1N0 early-stage breast cancer now accounts for more than 50% of the tumors diagnosed in France. The prognosis of these tumors is good, even excellent in women ≥ 65 years of age, with specific survival of 98% at 5 years. The treatment of these tumors combines breast-conserving surgery and external whole breast irradiation for 6.5 weeks. A true de-escalation of treatment is taking place with these tumors, both surgically and medically. Surgery therefore now prefers breast-conserving methods in combination with exeresis of the sentinel lymph node only. In the same way, in many international studies, radiotherapy has been evaluating the possibility of reducing both: * the irradiation volume at the excision site (partial irradiation) * the duration of this irradiation (accelerated radiotherapy) Between 2004 and 2007, the CRLC \[Regional Anti-Cancer Center\] evaluated the feasibility and the oncological results of intra-operative partial irradiation via a phase II study in women 65 years of age and older with T1N0M0 hormone-sensitive tumors with a good prognosis. From 2010 to 2013, the ICM carried out an observational study of these tumors with an excellent prognosis. In July 2009, the American Society for Radiation Oncology (ASTRO) published a consensus statement with specific recommendations and indications for accelerated partial breast irradiation (APBI). This APBI technique has been developing in France over the past 5 years within the framework of clinical studies and in compliance with the 2012 recommendations of the French National Cancer Institute. This APBI can be given by 3D external radiotherapy or, as in this study, by intra-operative radiotherapy (IORT) in order to obtain optimal precision and spare as much of the surrounding healthy tissue as possible. The Investigator therefore propose a cohort study to prospectively analyze the results of this technique applied to the indications strictly defined by the ASTRO.