ESTRO 38 Abstract book

S1182 ESTRO 38

Purpose or Objective The standard treatment of locally advanced cervical carcinoma is radiochemotherapy, including concomitant external beam radiation (EBRT) with weekly Cisplatin and brachytherapy (BT). The electronic brachytherapy (XB) is a treatment option for breast, skin and gynaecological cancer. Our objective is to present our experience using electronic brachytherapy for cervical cancer. Material and Methods We present 8 patients with locally advanced cervical carcinoma. They were treated between May/2016 and August/2018 with EBRT, 46Gy in 200cGy fractions, using intensity-modulated radiation therapy (IMRT) and image- guided radiation therapy (IGRT) techniques concomitant with Cisplatin 40mg/m 2 followed by XB guided by magnetic resonance imaging (MRI). The total dose administered was 28Gy in 4 fractions given in two consecutive weeks (Thursday-Friday). We analysed the median dose in bladder, rectum and sigmoid D2cc with XB comparing the doses with Ir192. Toxicity was analysed according CTCAE 4.0 scale. Results After EBRT, six of the patients presented a complete response and the other two a partial response with a residual tumour <3cm. The mean doses received were: CTV HR 90: 112,55%, CTV HR 98: 95,88%, CTV IR 90: 59,03%, CTV IR 98: 63,67%. The mean V150 (cm3) with XB vs. Ir192 were: 23.4 vs. 20.7 and the V200 were: 13.8 vs. 11.8. In organs at risk (OAR) the median dose in bladder with XB vs. Ir192 was: 2cc 60.4% vs. 60.7%. In rectum XB vs. Ir192 was: D 2cc 33.7% vs. 43.9. In sigmoid XB vs. Ir192 was: D 55.4%vs. 58.3%. The mean following time is 13 months (range 2-29). Acute toxicity was observed: mucositis was observed in 4 patients (2 patients G1 and 2 G2); genitourinary (GU) toxicity was observed in 2 patients (G1) and gastrointestinal (GI) toxicity in 1 patient. At 3 months after treatment only 1 patient presents mucositis G1. After the XB treatment 7 patients are in complete response and 1 patient died from systemic progression. Conclusion The XB with tandem and ovoids is an appropriate technique on selected patients with residual tumour <3cm and without parametrial invasion. The dose received by the organs at risk with the XB is less compared to Ir192, with a good coverage of the PTV with excellent results as for toxicity. EP-2138 Rectal and urinary toxicity in patients with cervical carcinoma treated with brachytherapy V. Garcia Jarabo 1 , S. Cordoba Largo 1 , M. Ramirez 1 , D. Martínez 1 , M. Gaztañaga Boronat 1 , C. De la Fuente 2 , G. Marquina 1 , A. Ortega 1 , R. Mendez 1 1 Hospital Clinico San Carlos, Radiation Oncology, Madrid, Spain; 2 Hospital Universitario Puerta de Hierro Majadahonda, Radiation Oncology, Madrid, Spain Purpose or Objective To asses dosimetric factors predicting rectal and urinary morbidity and describe vaginal toxicity in patients treated with chemoradiation (CRT) and image-guide brachytherapy (IGBT-MRI) for locally advanced cervical cancer. Material and Methods From November 2010 to February 2016 we treated 64 patients (p) with stages IB-III cervical carcinoma. Mean age: 54.6 years (30-88). TNM stage: I: 4p, II: 54p and III: 6p. Histology: epidermoid: 49p; adenocarcinoma: 15p. All patients were treated with CRT and 3D-based planning intracavitary/interstitial IGBT, using the GEC-ESTRO recommendations for defining high-risk clinical target volume (HR-CTV). Equieffective doses at 2 Gy (EQD2) were calculated, applying linear quadratic model. Statistical analysis: chi-square test for comparing

Material and Methods Five female patients with uterus cancer were treated with HDRBT Ir-192 source using intra-cavitary Miami applicator with 7 channels. Brachytherapy plans were generated using IPSA inverse planning module of MasterPlan Treatment Planning System (TPS). For the purpose of this study the same five patients were re-planned with HDR Ir- 192 source but using only the central channel of Miami Applicator. Next step was to export all five patients (CT datasets and structure sets) to BrachyVision (Eclipse) TPS (Varian, Palo Alto, USA) and plan them with Xoft Axxent 50kVp electronic x-ray source. Due to the fact that same CT datasets and structure sets were used for re-planning process with BrachyVision TPS patient geometry and applicator geometry did not change. The best mimic of Miami applicator in BrachyVision TPS was Straight Tandem (1 channel) applicator overlaid with Miami applicator central channel. Re-planning was performed in such a way so that dosimetric coverage of the planning clinical target volume (Planning_CTV) achieved for two comparative treatment modalities (single-Iridium and 50 kVp) was matched with the plan patient was treated with. Results Comparison of doses to critical structures (small bowel, bladder and rectum) was performed and summarized in Table 1. Dose values of D (0.1 cc), D (1.0 cc) and D (2.0 cc) are averaged over 5 patients and given in Table 1, together alongside with range of doses and standard deviations. Average times for delivery of the plans were: 8.24 min. for HDR Ir-192 with Miami applicator with 7 channels, 5.38 min. for HDR Ir-192 with Miami applicator with 1 central channel and 6.23 min. for Xoft Axxent 50kVp electronic x-ray source with Straight Tandem 1 channel.

Conclusion Our results of retrospective dose comparison suggest that 50 kVp could potentially replace Ir-192 brachytherapy treatment modalities providing similar target coverage and similar maximum dose values to surrounding critical structures. Averaged treatment times are as well comparable between two treatment modalities. Further studies are needed however to investigate the impact of radio-biological effectiveness of 50 kVp photons when compared to Ir-192 emissions. EP-2137 Locally advanced cervical carcinoma treated with electronic brachytherapy: Our experience A. Miranda Burgos 1 , A. Méndez Villamón 1 , R. Ibáñez Carreras 1 , M. Gascón Ferrer 1 , A. Campos Bonel 1 , B. Garcia Gimeno 1 , E. Muñoz Sanz 1 , S. Lozares Cordero 2 , J. José Gutierrez 3 , I. Negredo Quintana 3 , I. Escartín Martínez 4 , G. Riazuelo Fantova 4 , M. Tejedor Gutierrez 1 1 Hospital Universitario Miguel Servet, Radiation Oncology, Zaragoza, Spain; 2 Hospital Universitario Miguel Servet, Medical Physics and Radiation Protection, Zaragoza, Spain; 3 Hospital Universitario Miguel Servet, Gynecology, Zaragoza, Spain; 4 Hospital Universitario Miguel Servet, Radiology, Zaragoza, Spain