ESTRO 37 Abstract book

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ESTRO 37

relevant OAR (D1cc) with and without balloon were recorded. The D1cc of the realized irradiation plan was compared to the D1cc of the virtually contoured OAR and statistically evaluated. Results In 31 cases at least one balloon catheter was administered without any acute complications. The total duration of the application time was increased by 5 min per balloon catheter. Serious late side effects occurred in one (3 %) case only. The median D1cc in the group with balloon (13.5 Gy) was significantly lower compared to the virtual OAR group without a balloon (15.5 Gy) with a corresponding median relative difference of -16.3 %. Conclusion The achievable significantly lower dose exposition of the adjacent OAR reduces the risk of side effects. This may be particularly important in case of oligo-metastasis since a more efficient irradiation of the CTV becomes possible consecutively. EP-2252 Bronchial brachytherapy- UCLH experience and patient outcomes G. Eminowicz 1 1 University College London Hospital, Radiotherapy Department, London, United Kingdom Purpose or Objective Brachytherapy (BT) can effectively palliate symptoms from endobronchial tumours. ABS guidance recommends bronchial BT for palliation in patients unable to have EBRT who have central obstructing lesions. Through retrospective review of practice at my centre I plan to understand the treatment delivered and subsequent patient outcomes aiming to guide future treatment protocols and potential research avenues. Material and Methods A retrospective review of the UCLH practice over a five year period (2011-2016) was undertaken. Data was gathered for all patients who underwent bronchial BT during this time period from patient notes and the electronic patient system. Dose prescription, treatment length, diagnosis, symptomatic response and survival were recorded. Results 44 patients were treated, total of 57 treatments. 2 patients received BT as a boost to radical EBRT. 42 were palliative. 55% were men, 45% women. 50% had primary lung cancer, 73% of which were NSCLC. 1 patient (2%) had amyloidosis. 47% had metastatic disease from other tumour sites including sarcoma, colorectal, breast, lymphoma, head and neck and oesophagus. At least 57% had received previous EBRT. Dose was prescribed to 1cm depth for all treatments. Median prescribed dose was 5Gy (range 3-8Gy) and all treatments were single fraction. 3Gy was applied for amyloidosis, third retreatment and as a boost to radical EBRT. Median treatment length was 5cm, range 3.5-11cm. Clinical response was reported in 90%, median duration 13 weeks. 72% responded for 3 months or longer, 34% 6 months or longer. In more recent years patients have undergone debulking previous to the delivery of BT but the numbers are too small to understand the clinical efficacy of this. Patients treated for critical obstruction had poor survival of 50% at 2 months. No grade 2 or higher haemorrhage was reported. Only 1 patient experienced significant breathing difficulties 2 weeks post procedure, treated as infection. Conclusion Bronchial BT is a safe and well tolerated palliative treatment. Patients in critical obstruction had a poorer prognosis suggesting bronchial BT should be considered earlier in their treatment pathway for extensive endobronchial disease. Response to treatment was clinically meaningful and durable despite doses being less than that recommended in ABS guidance (10-15Gy). We

therefore hope to gain increased response rates by increasing the doses in line with guidance. Laser debulking followed by BT may be an effective palliative treatment strategy for patients. A proposed study design is therefore randomisation of patients undergoing laser debulking to BT or no BT. EP-2253 Intraoperative high-dose-rate brachytherapy using the Freiburg flap T. Muñoz Migueláñez 1 , R. Hernanz de Lucas 1 , R. Colmenares Fernández 2 , I. Pérez Muñoz 3 , L. Garro Guerrero 4 , L.J. Cabañas Montero 5 , S. Sancho García 1 1 Hospital Universitario Ramón y Cajal, Radiation Oncology, Madrid, Spain 2 Hospital Universitario Ramón y Cajal, Radiophysics, Madrid, Spain 3 Hospital Universitario Ramón y Cajal, Orthopedic Surgery and Traumatology, Madrid, Spain 4 Hospital Universitario Ramón y Cajal, Plastic and Reconstructive Surgery, Madrid, Spain 5 Hospital Universitario Ramón y Cajal, General Surgery, Madrid, Spain Purpose or Objective To describe the preliminary clinical outcomes of intraoperative high-dose-rate (IOHDR) brachytherapy using the Freiburg flap in our hospital. Material and Methods Between March 2016 and March 2017, fifteen patients received IOHDR brachytherapy using the Freiburg flap at the time of surgical resection. Of these patients 13 had sarcomas, 1 had Merkel cell carcinoma and 1 had melanoma. The mean age was 63.4 years (range 33-93). Negative margin (R0) was obtained in 14 patients and microscopically positive margins (R1) in 1 patient. Twelve patients received postoperative external beam radiation therapy (EBRT). The IOHDR dose was 15 Gy in 9 patients and 12 Gy in 6 patients and the mean EBRT dose was 46.7 Gy (range 44-54 Gy).

Results With a mean follow up of 13.51 months (range 3.83- 18.93) the local control was 100%. There were no G3-4 intraoperative o postoperative complications. Acute toxicities were wound infection in 3 patients and poor healing with wound dehiscence in 5 patients. No late toxicities were seen. Conclusion IOHDR brachytherapy using the Freiburg flap is a feasible, save and well-tolerated component of