Intra-Operative Electron Boost and Hypofractionated Whole-Breast Irradiation During Breast-conserving Treatment (BCT)

Study population: See Points 4.1 und 4.2 Inclusion/Exclusion criteria of the entire protocol Operation: * Lumpectomy / segmentectomy / tumorectomy with sufficient safety margins (see above). Lymph node assessment must follow a sentinel node concept. * Perioperative antibiotic prophylaxis is mandatory * After IORT, radio-opaque clips have to be fixed at the tumor bed. Histology: R0-Resection is mandatory Chemotherapy: neoadjuvant:allowed adjuvant: allowed. There are no limitations towards special chemotherapeutic schemes and schedules. Radiotherapy: IOERT * IOERT is performed on mobile or fixed linacs * Reference dose: 11 Gy specified as maximum dose, with a minimum target volume dose of 90% encompassing the PTV (i.e. 10 Gy). WBRT * must start within day 36- 56 postoperatively (week 6 - 8 p.o.) in case of adjuvant hormonal treatment (or no further tumor specific medication) * In case of adjuvant chemotherapy, a time - gap between IOERT and WBRT up to 9 months is allowed. * Single reference dose per fraction: 2,7 Gy (ICRU) * Number of fractions: 15, Number of fractions per week: 5 * Total WBRT dose: 40,5 Gy RT of regional lymphatics: exclusion criterion Diagnostics of Local recurrence: * yearly mammographies, * optional breast sonography, MRI * LR has to be histologically confirmed Follow-up screening for detection of metastases (minimum requirements): * Chest X-Ray, optional * abdominal sonography, optional * lab tests incl. tumor markers, optional Assessment of acute toxicity of WBRT according to CTC-toxicity Scoring-systems: Assessment of late toxicity according to LENT-SOMA scoring-systems Assessment of cosmetic outcome according to 5-point- Scoring System (vanLimbergen) starting before WBRT, including photo documentation in standardized positions