ESTRO 36 Abstract Book

S344 ESTRO 36 _______________________________________________________________________________________________

simple mastectomy were the main surgical approaches (69.9%). Skin-sparing and nipple-sparing mastectomy were performed in 29.7%. Immediate reconstruction was done in 94% of patients, 85% with tissue expander with included or remote valve. The average volume expansion was 546.2 ml. Post-operative RT was performed in 162 patients (66.4%) with prescribed dose of 50 or 50.4Gy in 92.3%. Early complications were seen in 125 patients (50.8%), of which 25% required reoperation and 18.3% of the patients lost the implant. Local infection was significantly correlated with severe early complications. Only 10 patients (4.1%) had late complications. Of these, 8 underwent post-operative RT (5% of irradiated patients) and 2 (2%) were not irradiated (p = 0.327). In the univariate analysis, diabetes mellitus, smoking, neoadjuvant chemotherapy, expander with included valve, age over 50 years, BMI > 25 kg/m 2 were related to early toxicity (p < 0.05). In multivariate analysis, besides obesity, diabetes mellitus, expander with included valve and not performing neoadjuvant chemotherapy remained as variables related to early toxicity (p < 0.05). No correlation of the studied clinical variables with late toxicities was observed. RT was not related to high risk of early and late toxicities. Conclusion Approximately 50% of patients with alloplastic breast reconstruction presented early complications. Late complications were low in this population. RT did not increase the risk of severe complications after alloplastic breast reconstruction. PO-0659 Hypofractionated-accelerated concomitant boost in moderate-high risk breast cancer:phase I-II study M. Boccardi 1 , G. Macchia 1 , F. Deodato 1 , M. Ferro 1 , S. Cilla 2 , A. Ianiro 2 , S. Cammelli 3 , A. Farioli 4 , D. Smaniotto 5 , A.L. Angelini 6 , A. Di Stefano 7 , G.P. Frezza 8 , I. Ammendolia 3 , G. Tolento 3 , A. Zamagni 3 , V. Valentini 5 , A.G. Morganti 3 1 Fondazione di Ricerca e Cura "Giovanni Paolo II", Radiotherapy Unit, Campobasso, Italy 2 Fondazione di Ricerca e Cura "Giovanni Paolo II", Medical Physics Unit, Campobasso, Italy 3 University of Bologna, Radiation Oncology Center- Department of Experimental- Diagnostic and Speciality Medicine - DIMES, Bologna, Italy 4 University of Bologna, Department of Medical and Surgical Sciences - DIMEC, Bologna, Italy 5 Policlinico Universitario "A. Gemelli"- Università Cattolica del Sacro Cuore, Department of Radiotherapy, Rome, Italy 6 University of Bologna- S. Orsola-Malpighi Hospital, Medical Physic Unit, Bologna, Italy 7 Fondazione di Ricerca e Cura "Giovanni Paolo II", Gynecologic Oncology Unit, Campobasso, Italy 8 Ospedale Bellaria, Radiotherapy Department, Bologna, Italy Purpose or Objective To evaluate the results in terms of local control and late toxicity using intensity modulated radiotherapy with concomitant boost in breast cancer (BC). These results were compared with a control group (CG) of patients treated with standard 3-dimensional (3-D) radiotherapy Primary endpoint was local control. Secondary endpoints were late skin and subcutaneous toxicities. Patients with moderate-high risk (≥ 3 axillary nodes and/or pre- or peri- menopausal status and/or close resection margins) were enrolled and treated with forward-planned IMRT technique. Prescribed dose to the breast was 50 Gy in 25 fractions (fx) with a concomitant boost to the tumor bed of 10 Gy. In CG group, whole breast received a total dose of 50.4 Gy in 28 daily fx with a sequential boost to the plus sequential boost. Material and Methods

tumor bed of 10 Gy in 4 fx. Late skin and subcutaneous toxicity were evaluated using Radiation Therapy Oncology Group / European Organization for Research and Treatment Cancer (RTOG/EORTC) scoring scale. Results Four hundred and fifty one patients were included in our analysis (MARA-2: 321; CG:130). Median follow up was 52 months (range: 3-115). Five-year local control was 96.7% and 97.6% in CG and MARA-2 groups, respectively (p=0.676). At univariate analysis, patients treated with concomitant boost (MARA-2) showed a significant increase of late G1 and G2 subcutaneous toxicity (p<0.001). Five- year G1 subcutaneous late toxicity free-survival (LTFS) were 73.4% and 38.5% in CG and MARA-2, respectively. Moreover, 5-year G2 subcutaneous LTFS were 96.5% and 80.0% in CG and MARA-2, respectively. Five-year actuarial cumulative incidence of G3 late subcutaneous toxicity was 0.0% and 0.9% in CG and MARA-2, respectively. G1 and G2 late skin toxicities were similar in the two groups and no patients showed G3 ≥ late skin toxicity in MARA-2. Conclusion This study showed the feasibility of concomitant boost using IMRT technique in postoperative radiotherapy of BC with reduction of treatment duration and without significant increase of G > 2 late effects. Local control was excellent despite inclusion criteria. PO-0660 Partial breast re-irradiation with IMRT in patients with local failure after conservative treatment S. Dicuonzo 1 , R. Spoto 1 , M.C. Leonardi 2 , A. Surgo 3 , A. Viola 1 , M. Augugliaro 1 , F. Pansini 4 , F. Cattani 4 , V. Galimberti 5 , A. Morra 2 , V. Dell'Acqua 2 , R. Orecchia 6 , B.A. Jereczek-Fossa 1 1 European Institute of Oncology-University of Milan, Department of Radiation Oncology-Department of Oncology and Hemato-oncology, Milan, Italy 2 European Institute of Oncology, Department of Radiation Oncology, Milan, Italy 3 European Institute of Oncology-University of Milan, Department of Radiation Oncology-Department of Oncology and Hemato-oncology affiliation at the time of the study, Milan, Italy 4 European Institute of Oncology, Department of Medical Physics, Milan, Italy 5 European Institute of Oncology, Department of Surgery, Milan, Italy 6 European Institute of Oncology-University of Milan, Department of Medical Imaging and Radiation Sciences- Department of Oncology and Hemato-oncology, Milan, Italy Purpose or Objective The aim of the study is to evaluate acute and intermediate toxicity and clinical outcome of partial breast re-irradiation (re-PBI) with intensity-modulated radiotherapy (IMRT), using hypofractionation. Material and Methods This is a prospective clinical study including patients (pts) previously treated with whole breast radiotherapy (WBRT) who experienced in-breast tumor recurrence and underwent a second conservative surgery. Re-irradiation was limited to the tumor bed. Intensity modulated re-PBI was performed using Tomotherapy in helical modality or BrainLab-VERO step-and-shoot modality. Planning target volume (PTV) was generated by clinical treatment volume (CTV) with an isotropic margin expansion of 5 mm. Daily image guided irradiation was performed (megavoltage fan beam computerized tomography (CT) for Tomotherapy and kilovoltage cone beam CT for VERO). Planning objectives for PTV coverage were: V 100% ≥95%, V 95% ≥98%, D 0,03cc ≤110%. Acute toxicity was evaluated using RTOG/EORTC criteria, while late toxicity was recorded according to LENT/SOMA scale.