Abstract Book

S829

ESTRO 37

Material and Methods Five HIV patients diagnosed with cervical cancer were treated with RT between 2001 and 2015 in our center. Patients presented a range of age at the time of treatment, from 32-47 years (Average 40.6 years, median 44 years). The stages were IB1, IB2, IIIB (2 patients) and IVA. All patients received External Beam Radiotherapy with concurrent Platine-based chemotherapy, except one case that received radiotherapy alone. During cancer treatment, patients continued prescribed HIV treatment. Average follow-up at the time of assessment was 54.2 We observed a worsening in CD4 count from baseline (average 321.39 CD4, median 338 CD4) to the end of radiotherapy treatment (average 69.4 CD4, median 66 CD4). Patients also worsened viral load except in 2 cases that remained stable (Table 1) months. Results In terms of the evolution of oncological disease: 3 patients relapsed and died. Disease-free intervals were 1, 3 and 30 months. The other 2 patients were alive and free from disease at last control. Conclusion From these data, it can be seen that HIV patients diagnosed with cervical cancer worse HIV course during cancer treatment, in probable relation with exposition during the treatment period to 2 immunosuppressive stimuli (HIV and radio-chemotherapy). Likewise, these patients present greater aggressiveness regarding cervical disease, probably related to the immunodeficiency status of the patients and HPV association of HIV. However, it is a small series of patients that will be expanded to draw solid conclusions. EP-1533 SBRT replacing brachytherapy boost in operated endometrial cancer: a pilot feasibility study M. Possanzini 1 , S. Vieira 1 , J. Stroom 1 , C. Greco 1 1 Champalimaud Foundation, Radiotherapy, Lisbon, Portugal Purpose or Objective to reproduce adjuvant high dose rate brachytherapy (HDR-BRT) dose distributions and treatments by means of external beam fractionated stereotactic body radiotherapy (SBRT) in patients operated for intermediate and high risk endometrial carcinoma refusing or not eligible for BRT Material and Methods after informed consent submission, since December 2016 to September 2017, 9 patients (pts) not eligible or refusing BRT received SBRT on the vaginal cuff, with or without whole pelvis radiotherapy, after complete surgical staging with radical hysterectomy, bilateral salpingo-oophorectomy, pelvic and lombo-aortic lymphadenectomy and intra-abdominal cytology analysis 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