ESTRO 36 Abstract Book

S964 ESTRO 36 2017 _______________________________________________________________________________________________

3.6 Gy, 5.3 Gy and 4.6 Gy (p=0.045), respectively. Needle number showed inverse correlation with D2(r) (p=0.0264) and D1(r) (p=0.0433) parameters. Volume of HR-CTV correlated with D2(r) (r 2 =0.58) and D2(s) (r 2 =0.71). Conclusion Dosimetric results of combined intracavitary-interstitial IGABT were comparable to international literature. Dosimetric quality of these plans was significantly higher than intracavitary 2D and 3D optimized plans. Although 3D optimisation improved the quality of conventional 2D plans, IGABT plans resulted in even more homogeneous dose distribution and significantly lower doses to organs at risks. EP-1779 High-dose rate brachytherapy for inoperable endometrial cancer: definitive results L. Draghini 1 , F. Trippa 2 , M. Casale 2 , P. Anselmo 1 , F. Arcidiacono 1 , S. Fabiani 1 , M. Italiani 1 , E. Maranzano 1 1 Radiation Oncology Centre "S.Maria" Hospital Terni, Oncology Departement, Terni, Italy 2 Radiation Oncology Centre- “S.Maria” Hospital Terni, Oncology Department, Terni, Italy Purpose or Objective Purpose/Objective: To report our experience on three dimensional (3D) high-dose rate brachytherapy (HDR-BRT) in patients with stage I-III inoperable endometrial cancer. Material and Methods Material/Methods: Between March 2005 and April 2016 17 patients underwent HDR-BRT or HDR-BRT after external beam radiotherapy (EBRT) as definitive treatment. Median age was 79 years (range, 60-95), median KPS 90% (range, 60-100). Histology was endometrial adenocarcinoma in 14 (82%) and non-endometrial in 3 (18%) patients. In 15 (88%) patients FIGO clinical stage was I and in remaining 2 (12%) III. All patients were evaluated with computed tomography (CT) and endometrial biopsy, in 2 cases also magnetic resonance imaging (MRI) was done. Using the Fletcher applicator, a CT-based planning HDR-BRT was delivered. Follow-up was performed with physical examination, cervical cytology and CT or MRI. Local control (LC) was obtained when there was an interruption of vaginal bleeding. Results Results: All patients had a clinical LC, table 1 shows dose schedules used. After a median follow-up of 36 months (range, 6-131), 3 and 6 years LC rates were 86% and 69%, respectively. Cancer specific survival (CSS) at 1, 2 and 6 years was 93%, 85%, 85%, respectively. Age, stage, dose and type of radiotherapy did not result significant prognostic factors for LC and CSS. Only histology significantly influenced LC: for high risk histology (i.e., non-endometrial carcinoma or grade (G)3 endometrial adenocarcinoma) LC was 73% at 1 year and 36% at 6 years, for low risk histology (i.e. G1-2 endometrial adenocarcinoma) was 100% at 1 and 6 years (p=0.05). Acute toxicity was registered in 2 (12%) patients: G2 nausea and G2 proctitis in 1 patient (6%), G2 diarrhea, G2 anemia and G2 proctitis in 1(6%) patient. Two patients (12%) had G1 late rectal bleeding. Conclusion Conclusion: Our data show a good LC particularly in patients with stage I low risk histology endometrial cancer. Though number of patients is limited, definitive HDR-BRT could be an alternative treatment option for inoperable elderly patients with good compliance and limited toxicity. Histology is a prognostic factor for LC.

HDR-BRT = high-dose rate brachytherapy EQD2: Equivalent dose of 2 Gy per fraction calculated using the equation EQD2 = ([d+ α/β]/[2Gy+α/β]) derived from linear quadratic model. Legend: * patients submitted to external beam radiotherapy and brachytherapy EP-1780 Postoperative endometrium: 68Gy EQD2(α/β=3) at 2cc of vagina is related to G2 late toxicity. A. Rovirosa 1 , M. Aguilera 2 , C. Ascaso 3 , A. Herreros 4 , J. Sánchez 5 , J. Garcia-Miguel 6 , S. Sabater 7 , G. Oses 8 , P. Makiya 9 , S. Cortes 10 , J. Solà 6 , E. Agusti 11 , A. Huguet 6 , A. Garrido 6 , A. Lloret 6 , C. Baltrons 6 , M. Arenas 12 1 Hospital Clinic Universitari, Radiation Oncology Dpt., Barcelona, Spain 2 Hospital Universitario de Caracas, Radiation Oncology Dpt, Caracas, Venezuela 3 Faculty of Medicine- Universitat de Barcelona, Clinical Basics Dpt, Barcelona, Spain 4 Hospital Clínic, Radiation Oncology Dpt., Barcelona, Spain 5 Hospital Clinic Universitari, Finance Dpt, Barcelona, Spain 6 Hospital Clínic Universitari, Radiation Oncology Dpt, Barcelona, Spain 7 Hospital General de Alicante, Radaition Oncology Dpt, Barcelona, Spain 8 Hospital Clínic Universitari, Radiation Oncology, Barcelona, Spain 9 Hospital Rebagliati, Radiation Oncology Dpt., Lima, Peru 10 Hospital Clínic Universitari, Radiation Oncolgy, Barcelona, Spain 11 Hospital Clínic Universitari, Radiation Oncology Dpt, Barclona, Spain 12 Hospital Sant Joan de Reus, Radiation Oncology Dpt, Reus, Spain

Table 1. Dose schedules