ESTRO 37 Abstract book

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ESTRO 37

for endometrial cancer. Overall, 7 pts received a 3 times 5/7.5 Gy boost radiotherapy, to 5 mm from vagina mucosa and to the vaginal mucosa respectively, 2 were treated with exclusive 3 fractions SBRT 7/10.5 Gy per fraction to the vaginal cuff. Endorectal balloon, clumped urinary catheter with control of bladder repletion and vaginal BRT cylinder were employed to accurately reproduce pelvic anatomy and mitigate target motion. Use of real-time on-line tracking (Calypso®) permitted intra-fraction error control Results HDR-BRT dose prescription for SBRT treatment was reproduced in all cases, with 100% prescription dose to 5 mm CTV from vaginal mucosa, i.e. from the cylinder surface, plus 3 mm PTV. Vaginal mucosa CTV (i.e. cylinder surface), was encompassed by 150% prescription isodose. Doses to the organs at risk remained within the tolerance as defined in BRT guidelines and referring literature. All the programmed treatment fractions were administered in all patients. In 2 patients 5 mg of morphine were injected, due to a reduced tolerance to devices positioning, with a good tolerance after medication. All other patients were treated without medications needing. No greater than G2 acute toxicity was observed Conclusion SBRT can be considered in patients refusing or not eligible for HDR-BRT. Prospective trials are needed to better assess the outcome and adverse effects to define the feasibility of SBRT treatment in replacing BRT in this particular conditions EP-1534 International multi-institutional study of intraoperative radiotherapy for abdominopelvic tumors E. Balagamwala 1 , C. Leyrer 1 , M. Tom 1 , S. Potemin 2 , M. Kolar 1 , W. Polkowski 3 , E. Sperk 4 , F. Wenz 4 , J. Suh 1 , S. Amarnath 1 , P. Rose 5 , T. Hull 6 , S. Chalikonda 7 , H. Mahdi 5 , K. Stephans 1 , S. Cherian 1 1 Cleveland Clinic, Department of Radiation Oncology, Cleveland, USA 2 Regional Oncological Center of Krasnodar, Department of Colorectal Surgery, Krasnodar, Russian Federation 3 Medical University of Lublin, Department of Surgical Oncology, Lublin, Poland 4 University Hospital Mannheim, Department of Radiation Oncology, Mannheim, Germany 5 Cleveland Clinic, Department of Gynecologic Oncology, Cleveland, USA 6 Cleveland Clinic, Department of Colorectal Surgery, Cleveland, USA 7 Cleveland Clinic, Department of Hepatobiliary Surgery, Cleveland, USA Purpose or Objective Patients with locally advanced or recurrent abdominopelvic tumors in a previously irradiated field may benefit from intraoperative radiotherapy (IORT). Furthermore, IORT can be utilized as a boost prior to planned external beam radiotherapy when there is high concern for positive margins. We performed an international multi-institutional study to evaluate the outcomes of IORT in North America and Europe. Material and Methods We performed an IRB-approved retrospective review of all patients treated with IORT in the abdomen or pelvis at Krasnodar Medical University (Russia), Cleveland Clinic (USA), Medical University of Lublin (Poland) and University Hospital Manneheim (Germany). All patients were treated using the Intrabeam IORT system (Zeiss

International). The clinical and treatment records were reviewed and detailed information on initial cancer diagnosis, prior radiotherapy (RT), IORT, outcomes including local failure (LF), regional failure, distant failure as well as toxicities after IORT were collected. Statistical analyses was done using Kaplan-Meier analysis and Cox proportional hazards modeling. Results A total of 315 patients who underwent abdominopelvic IORT were included. The median age at IORT was 63 years and median follow-up after IORT was 19.1 months (range, 0.1-407 months). Initial pathology indicated 91.4% of patients had adenocarcinoma whereas 3.5% had squamous cell carcinoma and 5.1% had other histologies. 160 (51%) patients had received previous EBRT, and the median dose was 50.4 Gy in 28 fractions (range, 2500 – 6660 cGy). Median tumor size was 3.5 cm (range, 0.1-13 cm), IORT dose was 15 Gy prescribed to the surface (range, 6 – 36.45 Gy) and applicator size was 5 cm (range, 2 – 5 cm). At last follow-up, 266 (84%) patients were alive. After IORT, 35 (11%) of patients developed a LF and 57 (18%) patients developed metastatic disease. There was no difference in OS based on histology (p=0.14), however, patients with adenocarcinoma histology had a lower risk for developing LF (p=0.03). Risk for LR within the first 24 months was not different between patients based on margin status. Patients with positive margins had a higher risk for developing metastatic disease as well as LR after 24 months (p=0.02). Prior RT (p=0.80), tumor size (p=0.08) or IORT surface dose (p=0.14) were not predictive of local control. Toxicities included ureteral stent placement (11%), wound healing complications (4.1%), hydronephrosis (4.1%), neuropathy (2.2%), and gastrointestinal fistula (1%). Conclusion This series represents one of the largest IORT experiences reported in the literature. We found that the local control with IORT was excellent. Compared to patient with negative margins, patients with positive margins had similar risk for local failure in the first 24 months, however, they had a higher risk for developing distant metastases. Risk for toxicity after IORT was low overall. Our analysis suggests that IORT should be utilized in patients at high risk of having a local recurrence. EP-1535 Radiation Therapy for Locoregionally Recurrent Ovarian Cancer T.E. Ding 1 , A. Mohammad 1 , A. Sadozye 1 1 Beatson West of Scotland Cancer Centre, clinical oncology, Glasgow, United Kingdom Purpose or Objective Data to support benefit of radiotherapy in ovarian cancer is limited, We aimed to evaluate the effectiveness of radiotherapy for selected patients with locoregionally- recurrent ovarian cancer. Material and Methods We retrospectively analysed 54 cases treated at the Beatson West of Scotland Cancer Centre between March 1997 and May 2015. The Beatson Oncology Centre is one of the UK’s largest cancer centres, serving a population of 2.8 million. All cases were identified with a ten-digit code known as the CHI number . Cases were collected from an electronic database, case notes and the chemotherapy electronic prescribing system (chemocare). Ovarian cancer was staged according to the 2009 International Federation of Gynecology and Obstetrics system. Patients were selected to receive radiotherapy after multidisciplinary (MDT) discussion.