ESTRO 36 Abstract Book

S639 ESTRO 36 2017 _______________________________________________________________________________________________

LAD is considered to be receiving a high dose when over 10% of the contoured volume received 20 Gy or more. Results For all 32 patients, the plans are acceptable based on the criteria for whole heart and LAD arch . The results of this study showed that the mean doses to the three cardiac structures are 1,88 (range, 1,25-3,98 Gy) for the heart, 7.3 (range, 3,82-17,15 Gy) for the LAD arch and 9,64 (range, 3,24-27,84 Gy) for the LAD. Most important results shows, that for 11 patients the heart D mean was only 2,15 (range, 1,37 - 3,98), while a significant dose to the whole left anterior descending interventricular branch being delivered. We found 4 cases, in which the dose to the LAD arch was with marginal increase, but significant portion of the heart and whole LAD is included in the field. There were no cases where the dose to the LAD arch , LAD and whole heart dissociated. But in 7 cases the dose to the LAD arch was relatively low, however the dose to the whole LAD was significantly higher (14,6-37,6% of the contoured volume received over 20 Gy). Conclusion Evaluation of the mean dose to the heart only could lead to excessive heart irradiation. The results of the study indicate that it is necessary to assess the dose delivered to the whole heart as well as to the whole LAD for evaluation of the left breast irradiation treatment plan. This is very important to minimise the risk of clinically significant cardiac events after left breast radiotherapy. EP-1191 Postmastectomy locoregional irradiation to temporary tissue-expander or permanent breast implant M.A. Gerardi 1 , D.P. Rojas 2 , R. Ricotti 1 , M.C. Leonardi 1 , G. Riva 2 , D. Ciardo 1 , C.M. Francia 2 , R. Cambria 3 , R. Luraschi 3 , F. Cattani 3 , C. Fodor 1 , F. De Lorenzi 4 , M. Rietjens 4 , P. Veronesi 5 , A. Morra 1 , V. Dell'Acqua 1 , R. Orecchia 6 , B.A. Jereczek-Fossa 2 1 European Institute of Oncology, Department of Radiation Oncology, Milan, Italy 2 European Institute of Oncology - University of Milan, Department of Radiation Oncology - Department of Oncology and Hemato-oncology, Milan, Italy 3 European Institute of Oncology, Department of Medical Physics, Milan, Italy 4 European Institute of Oncology, Department of Plastic and Reconstructive Surgery, 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 (partially supported by a research grant from Accuray Inc. entitled 'Data collection and analysis of Tomotherapy and CyberKnife breast clinical studies, breast physics studies and prostate study”) is to evaluate acute and intermediate toxicity in postmastectomy patients with implant-based immediate breast reconstruction receiving locoregional intensity modulated radiotherapy (IMRT) with a hypofractionated scheme. Material and Methods Data of the first 121 consecutive post-mastectomy locoregional patients treated with Helical Tomotherapy between May 2012 and May 2015 with a hypofractionated scheme (2.67Gy/fr, 15 fractions) have been prospectively collected. Breast reconstruction was performed with temporary tissue expander implantation in 57% of patients (69/121 expander-patients) and with permanent prosthesis in 43% of patients (52/121 prosthesis-patients). Acute toxicity was evaluated using RTOG/EORTC criteria,

while late toxicity was recorded according to LENT/SOMA scale. Results All patients completed the treatment course without interruption for toxicity. In the expander group, one patient died for leukemia 20.3 months after radiotherapy and two had distant metastasis.Acute toxicity was assessed in 121 patients (mean follow up: 2.4 months, range: 0-8.1 months). No patient experienced grade >2 toxicities (edema, erythema or desquamation). No significant difference (p=0.06) in acute toxicities were observed between the type of allogenic reconstruction: 43.5% (30/69) of expander-patients and 26.9% (14/52) of prosthesis-patients presented toxicities of grade 2. The most common toxicity was edema, which was of grade 2 in 33.3% (23/69) of the expander-patients and 21.2% (11/52) of prosthesis-patients (p=0.141). Grade 2 acute erythema was observed in 14.5% (10/69) of expander- patients and 7.7% (4/52) of prosthesis-patients (p=0.249). Statistically significant (p=0.04) higher incidence of grade 2 edema was found in patients with high BMI. This was found also in the prosthesis-patient subgroup (p=0.05).Intermediate toxicity was evaluated at a median follow up of 14.2 months (range: 5.8-35.0) on 85 patient (54 expander-patients and 31 prosthesis-patients). No grade ≥2 skin dryness, telangiectasia, ulcer, hypo- and hyper-pigmentation were reported (Tab.1).

Conclusion Acute toxicity of Helical Tomotherapy-based IMRT after immediate breast reconstruction was satisfactory and intermediate toxicity was acceptable. Based on this preliminary analysis, hypofractionation might be considered also in the settings of locoregional treatments, providing advantages for patients’ convenience and for fruitful use of resource. EP-1192 Assessment of quality of life in phase III clinical trials of radiation therapy in breast cancer G.N. Marta 1,2 , F.Y. Moraes 3 , E.T. Leite 2 , E. Chow 4 , D. Cella 5 , A. Bottomley 6 1 Hospital Sírio-Libanês, Radiation Oncology, São Paulo, Brazil 2 Instituto do Câncer do Estado de São Paulo ICESP - Faculdade de Medicina da Universidade de São Paulo, Radiation Oncology, Sao Paulo, Brazil 3 Princess Margaret Cancer Center- University of Toronto, Radiation Oncology, Toronto, Canada 4 Sunnybook Odette Cancer Centre- Sunnybrook Health Sciences Centre, Radiation Oncology, Toronto, Canada 5 Northwestern University, Medical Social Sciences,