ESTRO 37 Abstract book

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ESTRO 37

was 17.1-175cm 3 . The median D10 and D2 for the lungs were 29.4% and 38.1% reference dose, respectively. The median skin dose was 43.7% reference dose (range 17- 68%). The median PTV100 was 95%, DHI 0.68 and COIN 0.69. The median follow-up for 218 patients was 87 months (range 61-133 months). There were no late serious complications. In the group of 218 patient we found 4 failures (1.83%), including 3 local recurrences and one case of distant metastases. Conclusion Accelerated Partial Breast Irradiation Using Sole Interstitial Multicatheter High-Dose-Rate Brachytherapy allows to spare critical organs from unnecessary radiation. In our group of patients with at least 5-year follow-up, implant parameters were satisfying, correlated with good tolerance and effectiveness. OC-0401 Accelerated Partial Breast Irradiation: Experience with 325 patients (Catalan Institute of Oncology) M. Laplana Torres 1 , D. Roura Secondulfo 2 , C. Gutiérrez Miguélez 1 , D. Najjari Jamal 1 , S. Comas Anton 1 , M. García Casellas 1 , S. Moreno Almagro 3 , O. Jordi Ollero 3 , E. Martínez Pérez 1 , J. Pera Fabregas 1 , F. Guedea Edo 1 1 Institut Català d'Oncologia - L'Hospitalet de Llobregat, Radiation Oncology, Barcelona, Spain 2 Hospital Universitario de Donosti, Radiation Oncology, Donosti, Spain 3 Institut Català d'Oncologia - L'Hospitalet de Llobregat, Medical Physics, Barcelona, Spain Purpose or Objective To describe our experience with 325 cases of APBI, related toxicity, LC and OS. Material and Methods From February 2004 to June 2017, 325 procedures of APBI were performed in our department. 43were treated under an internal phase II trial performed between 2004 and 2005; 27 patients were included in the European randomised phase III trial, and the rest (255), out of trial. All these patients belonged to the 'suitable group” recommended by the GEC-ESTRO (289 cases); or were part of a second conservative procedure (36 cases). In most cases procedure was performed postoperatively although in 79 cases the catheters were inserted at the same time of the lumpectomy. We are going to describe our results in all the patients treated with APBI for primary treatment received until 30 June 2017, excluding the relapses (267 cases). The fractionation used was 10 fractions of 3.4 Gy in the phase II trial, and 8 fractions of 4 Gy in the European phase III trial. Other fractionations used were 7 fractions of 4.3 Gy or a single dose of 16 Gy in elderly or fragile patients. In all cases, the interval between fractions was at least 6 hours.

frequent histology type (86.8%).With a median follow–up of 40months (range: 36- 43), we observed 2 local relapses (3.8%) [1 st pt: tumor size = 30 mm, security margins< 1 mm; 2 nd pt: tumor size = 20 mm, security margins < 1 mm)] and 1 axillary relapse (1.9%). The3-y LRFS, SS and OS rates were 95.3%, 100% and 93.4%. Acute toxicity occurred in 29 pts (58%) with 71 events. The most frequent acute toxicity was grade (G) 1fibrosis (45.2% of treatments),3 pts (6%) presented G3 acute toxicity (2 breast hematomas, 1 breast abscess). No ≥G3 late toxicity was observed while 15 late toxicities occurred (G1: 12 events [80%]) mainlyG1 breast fibrosis and visible puncture site scar). The rate of excellent cosmetic outcome was 75.4%. Conclusion We reported promising and encouraging clinical outcome of a post-operative single fraction of MIB ABPI in the elderly. This approach leads to consider a Hyper-APBI as an attractive alternative to intra-operative radiation therapy while 100% of the patients are good candidates for APBI in regards to the post-operative pathological report. More mature results (number of patients and follow-up) are needed. OC-0400 Eleven-Year Results Of Interstitial HDRBT APBI After BCS For Low-Risk Breast Cancer S. KELLAS-SLECZKA 1 , B. Bialas 1 , M. Szlag 1 , P. Wojcieszek 1 , M. Fijalkowski 1 , A. Cholewka 1 , M. Jarzab 2 , B. Lange 2 , T. Krzysztofiak 1 1 Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Brachytherapy Department, Gliwice, Poland 2 Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, III Department of Radiotherapy and Chemotherapy, Gliwice, Poland Purpose or Objective The role of APBI for patients with low-risk breast cancer has gained popularity as an alternative to the conventional whole breast irradiation (WBI) with external beam radiation. Multicatheter interstitial brachytherapy with flexible catheters located around the lumpectomy cavity is one of the oldest APBI techniques with the longest experience. The aim of the study was to report the results of 218 patients with at least 5-year follow-up treated with APBI using interstitial multicatheter high-dose-rate brachytherapy (HDR-BT) after breast-conserving surgery. Material and Methods From July 2006 to October 2017, 443 women with low- risk invasive and ductal carcinoma in situ after BCS underwent APBI using interstitial multicatheter HDR brachytherapy at our department. In the analyzed group, 218 patients were followed up for 5 years or longer. The inclusion criteria were: ZUBROD 0 or 1, age ³50 years, T1-2N0M0, T≤3cm, unifocally, invasive carcinoma without neuroinvasion, angioinvasion, minimal surgical margin 2mm or DCIS with minimal margin at least 5mm, without EIC (extensive intraductal component), positive estrogen receptors. The time between surgery and HDR-BT was more than 12 weeks. 78% of the analyzed patients underwent APBI under local anesthesia. The total dose was 32Gy in 8 fractions delivered twice-daily with a minimum 6-hour break. The primary endpoint was local recurrence. Results The median age was 62 years (range 47-86 years). All patients completed treatment without interruptions. There were no serious complications during the procedure. In 18% of the patients a hematoma following catheter insertion was noticed, which typically resolved within 2 weeks. The treatment was well tolerated. Near 2% of the patients developed local inflammation, requiring oral antibiotic therapy. In almost 20% of cases, prophylactic antibiotic therapy was applied. PTV range