ESTRO 38 Abstract book

S1173 ESTRO 38

From this study, it was revealed that a change in the dosimetric index of DVH occurs in the interfraction uncertainty of the SAVI applicator. In the future, it is suggested that it is necessary to consider the robustness of the plan from the interfraction change and the necessity of re-planning. EP-2119 HDR BRT boost in breast cancer: postoperative vs intraoperative procedure, long-term outcomes F. Piro 1 , D. Cosentino 1 , A. Martilotta 1 , A. Massenzo 1 , U. Piro 1 , G. Tocci 1 , L. Marafioti 1 1 Ospedale Mariano Santo, Radiotherapy Center, Cosenza, Italy Purpose or Objective To evaluate which is the best BRT technique, we studied the impact on survival and longterm outcomes of two HDRBRT procedure boost: postoperative (POST) vs From January 2001 to February 2005, 75 pts. with breast cancer were treated with intraoperative (29) or postoperative (46) implant consisting of 3 fractions of 350 cGy each, 6 hour apart, before or after Whole Breast Radiotherapy (50 Gy/5 weeks). To provide coverage of tumor bed implant done with afterloading catheters at the time of quadrantectomy or after the external beam. All pts. underwent CT to evaluate the needles insertion according this criteria: 3 cm at least around surgical cavity (when surgical clips available) or 3 cm around surgical scar in case of postoperative. If intraoperative: clips to mark the walls of the excision cavity same treatment volume. All implants had markers at the extremities of each catether plus other marker on the apex of the implant out of the breast (skin points). Implants planned with a semi- 3-D technique aided by simulator, target volume determined by surgical clips and dose to the skin by the catether markers. Survival comparison with Kaplan Meier Median follow up: 8,2 years (1-16 years). Age: median 57 (26-77). Survival comparison median 10,24 years (POST) vs median 2.74 (INTRA) P=0.95 (not significant). In POST group 11/46 pts. (24%) had relapse or metastasis vs INTRA 8/29 (27%). The rate of relapse: 6.5 INTRA vs 6.8 POST. Lymph node status (guidelines of ABS not available at the time of treatment) for relapse or metastasis not significant. Ten years local relapse-free rate was 90 INTRA vs 89% POST. Conclusion Comparing these different boost techniques we did not find any difference in loco-regional recurrence, in metastasis-free and overall survival. Although it is preferable to perform intraoperative boost, these data show that postoperative mode, if properly performed according to the guidelines, is alternative to the first one. Also the treatment volumes should not be underestimated. INTRA is easier to carry out. EP-2120 Analysis of our Accelerated Partial Brachytherapy Irradiation (APBI) learning curve S. Pinto 1 , A. Pereira 1 , P. Fernandes 2 , L. Trigo 2 1 Instituto Português de Oncologia do Porto Francisco Gentil- EPE, Medical Physics, Porto, Portugal; 2 Instituto Português de Oncologia do Porto Francisco Gentil- EPE, Brachytherapy, Porto, Portugal Purpose or Objective To analyse our learning curve of APBI treatments with multi-catheter image-guided brachytherapy (BT), based on the experience obtained with the 60 initial applications. intraoperative (INTRA). Material and Methods method Results

Material and Methods We changed the APBI treatment technique in November 2016 from an applicator-based planning (with a dosimetry based on isodose curves according to the Paris system without an imaged target volume - theoretical plan with rigid needles), to a volume-based planning (with target volume and OAR contouring, as well the reconstruction of plastic catheters in a CT image). Following GEC ESTRO (1)(2) , ABS (3) and ASTRO (4) recommendations for the implant technique and the AAPM TG43 formalism for the dosimetry, all plans were made with inverse planning (IPSA) and, when necessary, with graphical optimization, in Oncentra Brachy (version 4.5.3 - Elekta). Patients were treated with a high dose rate (HDR) modality (8 fractions, 2 per day, with 32Gy of prescribed dose) in a microSelectron from Elekta, with a difference of at least 6 hours between the fractions. To evaluate our learning curve, the patients were chronologically divided into three groups of 20. The following parameters were analysed: V PD , V 1.5xPD , V PTV , V 100 , V 150 , V 200 , DHI, COIN, dose to the skin (0.2cm 3 and 1cm 3 , defined 5mm below the body contour), and the number of implanted tubes. Results The following table shows the analyzed dose-volume parameters and the recommended limits. Conclusion Regarding the parameters related to the target coverage (V 100 and COIN), a significant improvement was observed over time. Regarding the parameters related to the implant (V PD , V 1.5xPD and DHI), a loss in homogeneity and the consequent appearance of high dose points (V 200 ) was observed over time. Following recommendations, an improvement in the homogeneity of our implants and a better compromise between all parameters involved (target coverage, dose homogeneity, excessive dose volumes and dose in the OAR) should be achieved. It is noteworthy that the skin dosimetric values have always remained well below the recommended limits. Our dosimetric quality indices evolution shows that we are on the right track. EP-2121 Intraoperative radiotherapy in early breast cancer: short -term outcomes J.R. Oliver 1 , E. Hernando Almudi 1 , C. Casamayor Franco 1 , C. Vallejo 1 , G. Molina Osorio 2 , A. Miranda Burgos 2 , M. Lanzuela Valero 2 , R. Ibáñez Carreras 2 1 Hospital Universitario Miguel Servet, General Surgery, Zaragoza, Spain; 2 Hospital Universitario Miguel Servet, Radiation Oncology, Zaragoza, Spain Purpose or Objective The aim of this abstract is to evaluate the short-term outcomes of using Intraoperative radiotherapy (IORT) in early breast cancer in our center. Material and Methods A prospective review was performed. 233 cases of early breast cancer were treated with breast conserving surgery (BCS)/oncoplastic surgery and IORT from 13/05/2015 to 16/08/2017. A low energy X-rays system (Axxent Xoft device) administered a 20-Gy dose at the tumor bed. All patients were evaluated by a multidisciplinary Tumor Board. Selection criteria for IORT as radiotherapy alone were: age ≥50 y.o., no BRCA mutations, clinical tumor sice up to 3cm, none linfovascular invasion, ER +, not multicentric or multifocal tumors, histology of IDC, cN0 and no neoadjuvant therapy. The rest of the patients who did not meet the criteria were finally treated with IORT as a boost. Clinical and radiological evaluations (ultrasound and mammographic exams) were performed routinely. Complications reported are: dermatitis, hematoma, seroma, infection, pain, fibrosis / fat necrosis, ulcer and fistula (delayed healing of a small side of the surgical wound).