Abstract Book

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ESTRO 37

EP-1270 Randomized of hypofractionated WBI versus APBI using VMAT: early toxicity results F. De Rose 1 , D. Franceschini 1 , C. Iftode 1 , T. Comito 1 , A. Tozzi 1 , C. Franzese 1 , L. Di Brina 1 , E. Clerici 1 , G. D'Agostino 1 , P. Navarria 1 , S. Tomatis 1 , M. Scorsetti 1 1 Istituto Clinico Humanitas, Radiotherapy and Radiosurgery, Rozzano Milan, Italy Purpose or Objective We designed a study to evaluate toxicity and cosmesis of Accelerated Partial Breast Irradiation (APBI) using external intensity–modulated radiotherapy (VMAT-RA), compared to hypofractionated Whole Breast Irradiation (WBI) in postmenopausal women with early breast cancer (BC) undergoing conserving surgery. Material and Methods Postmenopausal women affected by low risk early BC (hormonal receptor positive, tumor size less than 3 cm, node negative) were randomly assigned in a 1:1 ratio to receive either hypofractionated WBI or APBI using VMAT. Patients in the APBI arm receive a total dose of 30 Gy to the tumor bed in five fractions every other day. The WBI arm receive 40.5 Gy to the whole breast, and 48 Gy to the tumor bed in 15 fractions with Simultaneous Integrated Boost (SIB) technique. Primary end-point is the evaluation of toxicity and cosmesis outcome. This trial is registered with ClinicalTrials.gov, number NCT02375048. Acute toxicity and late toxicity were scored according to CTCAE v.4.0. Cosmesis was assessed according to the Harvard scale. Results From November 2014 to September 2017 we enrolled 213 patients. Here we present data on the first 96 patients with at least 6 months follow up. 47 patients were randomized to APBI arm, 49 patients received hypofractionated RT. Treatment was globally well tolerated. No G3-4 toxicity was recorded. In the APBI arm, acute toxicity was reported in 12 patients (25.5%), mostly asthenia (G1 4 cases, G2 1 case) and skin erythema (G1 6 cases). In the whole breast arm, toxicity was reported in 34 patients (69.4%), mostly asthenia (5 patients G1, 1 patient G2), skin toxicity (G1 in 21 cases, G2 in 8 cases) and breast pain (7 cases). With a median follow up of 8.2 months (range 6-32 months), no patients experienced local or distant recurrence. In the APBI arm, 13 patients (27.6%) reported G1 toxicity, mostly fibrosis (7 cases) and breast pain (5 cases). In the WBI arm, 34 patients reported (69.4%) late side effects, in three cases G2 (2 cases of skin erythema and 1 case of fibrosis). At the last follow up, in the APBI arm cosmesis was rated excellent in 38 patients (80.8%) and good in 9 (19.2%) while in the WBI arm it was excellent in 27 patients (55.1%), good in 19 (38.8%) and fair in 3 (6.1%). Conclusion The current trial is still ongoing, however the preliminary results here reported seems to confirm that APBI with VMAT technique is feasible and safe. More patients and longer follow up data are needed. EP-1271 Margin Status And Local Relapse After Breast- Conserving Therapy M.C. Cruz muñoz 1 , J.L. Muñoz Garcia 2 , F. Ropero Carmona 2 , M.A. Gonzalez Ruiz 2 , P. Simón Silva 2 , J. Quirós Rivero 2 , A. Corbacho 2 , Y. Ríos Kavadoy 2 , J.J. Cabrera Rodriguez 2 1 Hospital Infanta Cristina, Oncology Radiotherapy, utrera, Spain 2 Hospital Infanta Cristina, Oncology Radiotherapy, Badajoz, Spain Purpose or Objective The presence of positive margins after conservative treatment in breast cancer is a prognostic factor of local recurrence. The objective of our study was to e valuate phase II study

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Conclusion Pencil beam scanning proton therapy is suitable for left- side breast cancer with acceptable acute and late skin toxicity. It allows minimal doses to the heart, lungs and contralateral breast. This should be beneficial to patients with long life expectancy and also to patients with associated heart diseases. EP-1269 Adjuvant chemotherapy and hypofractionated VMAT treatment with SIB for early stage breast cancer D. Franceschini 1 , F. De Rose 1 , C. Iftode 1 , G.R. D'Agostino 1 , P. Navarria 1 , P. Mancosu 1 , A. Fogliata 1 , S. Tomatis 1 , M. Scorsetti 1,2 1 istituto Clinico Humanitas, Radiotherapy And Radiosurgery, Rozzano Milan, Italy 2 humanitas University, Biomedical Sciences, Rozzano- Milan, Italy Purpose or Objective To evaluate acute toxicity and cosmetic outcomes of hypofractionated simultaneous integrated boost (SIB) approach with Volumetric Modulated Arc Therapy (VMAT) as adjuvant treatment after breast-conserving surgery and adjuvant chemotherapy. Material and Methods Patients presenting early-stage breast cancer were enrolled in a phase II trial. Eligibility criteria were as follow: age >18 years, invasive cancer or DCIS, Stage I to II (T <3 cm and N ≤ 3), breast-conserving surgery, any systemic therapy was allowed. All patients underwent VMAT-SIB technique to irradiate the whole breast with concomitant boost irradiation of the tumor bed. Doses to whole breast and surgical bed were 40.5 Gy and 48 Gy respectively, delivered in 15 fractions over 3 weeks Acute skin toxicities were recorded according to RTOG scoring criteria and late skin toxicities according to CTCAE v4.0. Cosmetic outcomes were assessed as excellent/good or fair/poor according to the Harvard scale. Results Between August 2010 and August 2015, 767 consecutive patients were treated. A subset of 154 patients underwent adjuvant chemo- therapy. Median age was 55.7 year (range 26.3 – 77.5). The median follow up was 42 months (range 24-78). At the end of RT treatment skin toxicity profile was G1 in 50% of the patients, G2 in 10.9%. At six months skin toxicity was G1 in 27.7% of patients, G2 in 1.9%, no G3 cases. At 2 years of follow up skin toxicity was G1 in 13.8% of patients, no G2 or G3 cases; cosmetic outcome was excellent in 64.1% and good in 35.9% of patients undergone chemotherapy. We recorded no significant statistically differences compared to other patients. Conclusion Hypofractionated VMAT treatment with SIB after breast conservative surgery in patients undergone adjuvant systemic therapy was safe and well tolerated in terms of acute and early late settings. Cosmetic results were also good or excellent in the most of patients. Long-term follow-up data are needed to assess late toxicity and clinical outcomes.