ESTRO 2020 Abstract Book

S365 ESTRO 2020

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were treated between 2010 and 2018. In those women who received adjuvant radiotherapy, it was performed using intensity-modulated radiotherapy, with or without vaginal brachytherapy. The study cohort was evaluated using Kaplan–Meier estimates of recurrence-free survival (RFS) and overall survival (OS) and proportional hazard modeling. Results In total, 161 patients were considered for this study (52 stage IIIA, 9 stage IIIB, and 100 stage IIIC patients). Of these, 154 patients (96%) received an adjuvant treatment—chemotherapy (67; 42%), radiotherapy (29; 18%), or combined chemo-radiotherapy (58; 36%). The 5- year RFS and OS were 61% and 80% for patients treated with adjuvant chemotherapy, 75% and 86% with adjuvant radiotherapy, and 69% and 89% with both adjuvant radiotherapy and chemotherapy, respectively. In the stage IIIC cohort, patients who received adjuvant radiotherapy, with or without chemotherapy, (n = 59) had an improved 5-year RFS (74% vs 54%, p = 0.045) and OS (92% vs 72%, p = 0.020) than those who received only adjuvant chemotherapy (n = 37). Adjuvant radiotherapy, with or without chemotherapy, was associated with an improved RFS for patients with an endometrioid histology (p = 0.048), with >2 positive lymph nodes (p = 0.014), and aged >60 years (p = 0.022). Conclusion In this era of intensity-modulated radiotherapy, the use of adjuvant radiotherapy, with or without chemotherapy, was associated with improved survival in women with optimally resected stage III endometrial cancer. In particular, it may be beneficial for patients with an endometrioid histology, with >2 positive lymph nodes, and aged >60 years. These findings should be further investigated in prospective clinical trials. PD-0658 Suboptimal dosimetric coverage of PET/CT hotspots is associated with recurrence for cervical cancer F. Lucia 1 , D. Visvikis 2 , V. Bourbonne 1 , J. Bert 2 , R. Abgral 3 , G. Dissaux 1 , O. Miranda 1 , O. Pradier 1 , M. Hatt 2 , U. Schick 1 1 Radiation Oncology department- University Hospital- Brest- France, Radiation Oncology department- University Hospital- Brest- France, Brest, France ; 2 LaTIM- INSERM- UMR 1101- Univ Brest- Brest- France, LaTIM- INSERM- UMR 1101- Univ Brest- Brest- France, Brest, France ; 3 Nuclear Medicine department- University Hospital- Brest- France, Nuclear Medicine department- University Hospital- Brest- France, Brest, France Purpose or Objective Patients with locally advanced cervical cancer (LACC) treated with chemoradiotherapy (CRT) have local recurrence rate of ~15%. Areas of high uptake on Pre- treatment 18 F-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography/computed tomography (PET/CT), denoted as “hotspots”, have been identified as preferential sites of local relapse. The purpose of this matched-pair study was to analyze the dosimetric coverage of these hotspots with high dose-rate brachytherapy (BT). Material and Methods Forty-two patients with recurrence after CRT for CC (20 with pelvic recurrence and 22 with distant recurrence) were matched to 42 patients without recurrence randomly selected from a larger population. Mean (±standard deviation) follow-up was 26±11 months. For each patient, a rigid registration of the CT from the pre-treatment PET/CT with the radiotherapy planning CT was performed using the 3D Slicer TM Expert Automated Registration

Cervix (C) is a circular structure, from the junction of vaginal canal to the uterus, presenting higher signal intensity than vagina The anatomo-radiological boundaries identified to recognize these structures are shown in Table 1.

Conclusion MRI was useful and feasible to identify and contour emerging female pelvic floor structures. This atlas could be employed for evaluation of OARs’ sparing in the era of high-conformal RT. PD-0657 Survival in optimally resected stage III endometrial cancer: adjuvant radiotherapy in the modern era J.L. CHEN 1 , C. Pan 2 , Y. Liou 3 , C. Kuo 4 , Y. Huang 5 1 National Taiwan University Hospital and National Taiwan University College of Medicine, Oncology, Taipei, Taiwan ; 2 National Taiwan University Hospital and National Taiwan University College of Medicine, Medical Research, Taipei, Taiwan ; 3 National Taiwan University Hospital, Laboratory Medicine, Taipei, Taiwan ; 4 National Taiwan University Hospital and National Taiwan University College of Medicine, Clinical Laboratory Sciences and Medical Biotechnology, Taipei, Taiwan ; 5 National Taiwan University Hospital and National Taiwan University College of Medicine, Radiology, Taipei, Taiwan Purpose or Objective Adjuvant treatment for stage III endometrial cancer is still undefined. This study investigates how tumor characteristics and adjuvant treatments (adjuvant chemotherapy, radiotherapy, or both) can influence survival in women with optimally resected stage III endometrial cancer in this era of modern radiotherapy. Material and Methods This multi-institutional study retrospectively reviewed patients with surgically staged endometrial cancer who