Abstract Book

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ESTRO 37

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 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.

Results After a median follow-up time of 62 months (range: 3-177 months), the ages observed were from 30-80yo with a median of 70yo and 88.8% were Stage I. Molecular Classification: 92.9% Luminal A. Average treated volume 157 cc (53-300 cc). Only 3 local recurrence, 2 axillary node relapse and 5 systemic relapses. Overall survival was 95.4% at 5 years; Specific survival 99.9% at 5 years; Disease-free survival at 5 years 95.6%; Local control at 5 years was 98.8%. We could not administer APBI as plannedin 2 cases.

Conclusion APBI is a comfortable method, especially in elder or fragile patients with very good local control. Our results are comparable to those published previously. OC-0402 IBTR: second conservative radio-surgical treatment with interstitial BT HDR. From 2D to 3D planning C. Cavallin 1 , C. De Sanctis 2 , A. Ala 3 , U. Monetti 4 , V. Richetto 5 , E. Madon 5 , S. Gribaudo 4 1 Ospedale Molinette University of Turin, Radiation Oncology, Torino, Italy 2 Ospedale Molinette University of Turin - P.O. S. Anna, Breast Unit, Torino, Italy 3 Ospedale Molinette University of Turin, Breast Unit, Torino, Italy 4 Ospedale Molinette University of Turin - P.O. S. Anna, Radiation Oncology, Torino, Italy 5 Ospedale Molinette University of Turin - P.O. S. Anna, Physics, Torino, Italy Purpose or Objective To evaluate lumpectomy followed by interstitial BT HDR as a suitable salvage therapy for second tumour or recurrence of breast cancer after conservative surgery and post-operative EBRT.