ESTRO 36 Abstract Book

S621 ESTRO 36 2017 _______________________________________________________________________________________________

Many studies reported local recurrence in patients treated with breast-conserving surgery (BCS) with less than 5% in a lapse of 5 years. However, the indication of a hypofractionated scheme after a Modified Radical Mastectomy (MRM) is not clearly established, since there is only one study with a 7-year follow-up which reported 3 patients with local recurrence. Due to the high number of patients requiring RT, we initiated this transversal and comparative study, at the Centro Médico Nacional Siglo XXI, IMSS. We compared hypofractionated and conventional schedules in order to evaluate acute toxicity and local control, including patients treated with BCS and MRM, between November 2012 and March 2016. Material and Methods We included 560 patients: 394 were treated with MRM and 166 with BCS. According to the radiotherapy schedule received, they were divided in 3 groups: 40Gy/15Fx, 42Gy/16Fx, and 50Gy/25Fx. Results At the end of the treatment, acute skin morbidity grade 1 was found in 57, 72 and 32% of the cases; grade 2 in 42, 27 and 64% for treatments with 40, 42 and 50 Gy, respectively, and grade 3 in 3% for a dose of 50 Gy in patients treated with MRM. Regarding BCS, skin morbidity grade 1 was found in 48, 66 and 23% of the cases, while grade 2 in 51, 33 and 73% for treatments with 40, 42 and 50 Gy, respectively, and grade 3 in 3% of patients treated with 50 Gy (Figure 1). After the first month, morbidity was reported in 489 patients (341 MRM and 148 BCS); mainly xerosis and hyperpigmentation; subacute morbidity (at third month) was reported in 346 patients (247 of MRM group and 99 of BCS group), mainly xerosis (Table 1). In follow-up studies, radiation pneumonitis was found in seven patients treated with MRM (2.8% of the total), regardless of the schedule received; they were still asymptomatic in the last follow-up. So far, we have an average 6-month follow-up after ending RT treatment with 226 patients (136 of them were treated with MRM, and 90 with BCS), with a maximum 3-year follow-up. In total, nine locoregional recurrences (LR) are reported, either on the chest wall, breast or the lymph node regions, while we found 14 systemic recurrences which are reported in one or more sites. Most LR were observed among patients treated with MRM, which may be associated with the patients undergoing radical treatments that generally have a more advanced clinical stage. Conclusion With these results we can conclude that it is safe to use hypofractionated treatments for patients with breast cancer treated either with MRM , with acute and subacute morbidity similar to that found in patients treated with conventional schedules, at least with a similar local control between the different schedules. It is required, however, to complete the long-term monitoring. EP-1154 Changes in skin microcirculation during radiation therapy for breast cancer E. Tesselaar 1 , A.M. Flejmer 2 , S. Farnebo 3 , A. Dasu 4 1 Linköping University, Department of Radiation Physics and Department of Medical and Health Sciences, Linköping, Sweden 2 Linköping University, Department of Oncology and Department of Clinical and Experimental Medicine, Linköping, Sweden 3 Linköping University, Department of Hand and Plastic Surgery and Burns and Department of Clinical and

EP-1152 Intraoperative radiotherapy for early breast cancer: a monocentric experience A. Baldissera 1 , L. Giaccherini 2 , I. Marinelli 3 , A. Parisi 4 , G. Siepe 2 , O. Martelli 1 , F. Salvi 1 , D. Balestrini 1 , C. Degli Esposti 1 , I. Ammendolia 2 , G. Tolento 2 , V. Panni 2 , G. Macchia 5 , F. Deodato 5 , S. Cilla 6 , A.G. Morganti 2 , G.P. Frezza 1 1 Ospedale Bellaria, Radiotherapy Department, Bologna, Italy 2 University of Bologna, Radiation Oncology Center- Department of Experimental- Diagnostic and Specialty Medicine - DIMES, Bologna, Italy 3 Sapienza University, Radiation Oncology Department, Rome, Italy 4 Istituto Oncologico Veneto IRCCSS, Radiation Oncology Department, Padua, Italy 5 Fondazione di Ricerca e Cura “Giovanni Paolo II”, Radiotherapy Unit, Campobasso, Italy 6 Fondazione di Ricerca e Cura “Giovanni Paolo II”, Medical Physics Unit, Campobasso, Italy Purpose or Objective Single-dose intraoperative radiotherapy (IORT) is an alternative treatment for selected cases of early stage breast cancer. The purpose of this study is to present preliminary results of patients treated with IORT at Bellaria Hospital, Bologna, Italy Material and Methods We analysed data of 108 women who underwent lumpectomy and IORT with primary intent. IORT treatment was performed with a dedicated mobile electron accelerator (21 Gy were prescribed at 90% isodose). Data collected were histopathology, adjuvant treatment, clinical tolerability, local recurrences and outcomes. Results From December 2011 to December 2015, 108 women (median age 72 years) were treated with IORT. 75% of patients were treated with adjuvant ormonotherapy and 11.1% with combined chemotherapy plus hormonotherapy. The median follow-up was 26 months (range 2-52). 82.4% of patients had disease that was <2 cm in size, 65.7% of patients had an infiltrative duct carcinoma. At the end of follow-up 89.9% had a G0-G2 grade of late parenchymal fibrosis and 69.4% of patients a good cosmetic result. One patient underwent a mastectomy after five months because of chronic fistula in the irradiated area. One patient had a local relapse in a different quadrant and one patient had an axillary lymph node recurrence. Only one patient developed systemic metastasis. One patient died from breast progressive disease. Conclusion IORT represents a safe and effective alternative treatment option in selected patients with early breast cancer. Low complication rate with good clinical and cosmetic outcomes support IORT as a treatment option for selected women. EP-1153 Post-Mastectomy Hypofractionated Radiotherapy for Breast Cancer Treatment C.S. Ortiz Arce 1 , A. Chagoya González 2 , E.N. Barrientos Luna 2 1 Hospital Regional de Alta Especialidad Bajío, Radiotherapy, León, Mexico 2 Centro Médico Nacional Siglo XXI- IMSS, Radiotherapy, Mexico City, Mexico Purpose or Objective Radiotherapy (RT) for Breast Cancer improves local control and provides benefit in overall survival; this is given mainly in daily fractions (Fx) over a period of 5-6 weeks. Hypofractionated schedules reduce the number of sessions, shortening the treatment time.

Experimental Medicine, Linköping, Sweden 4 Skandionkliniken, ----, Uppsala, Sweden