ESTRO 2020 Abstract book

S651 ESTRO 2020

survival (DFS), and local control (LC) were estimated using Kaplan-Meier method and compared using Log-rank test. Results Median follow-up time was 31 months (range,3-123). Median age at recurrence was 68 years (range,57-80). Median time from surgery to recurrence was 15 months (range,2-84). Initial FIGO (2009) stage was IA in 13/28 (46%), IB in 11/28 (39%), and II in 4/28 (14%). The histology was endometrioid in 21/28 (75%) and non-endometrioid in 7/28 (25%). 12/28 (43%) had FIGO grade 3. Invasion of bowel, bladder or ureter was present in 5/28 (18%). Salvage radiotherapy was HDR brachytherapy in 5/28 (18%), combined external beam and HDR brachytherapy 8/28 (29%), and external beam radiotherapy alone in 15/28 (53%). 10/15 (67%) patients treated with external beam radiotherapy alone received 45 Gy (1.8Gy/fraction) followed by a sequential boost (dose:9-18 Gy), while 5/15 (30%) received a single phase of 50 Gy (2.5 Gy/fraction). Median time to disease progression after salvage radiotherapy was 11 months (range,3-32). Local control rate at 3 years was 63.3%. 3-year and 5-year OS were 66.9% and 51.1%, respectively. Patients with non-endometrioid histology had significantly inferior OS compared to endometrioid histology (3-year OS 42.9% vs 75.2%, log-rank p=0.009). Invasion of adjacent structures was associated with poorer OS (3-year OS= 20% vs 77%, log-rank p=0.005). A trend for improved OS was observed for tumours ≤1.5cm (log-rank p=0.057) and with the use of brachytherapy (log- rank p=0.2). Median DFS was 16 months. 3-year and 5-year DFS were both 24%. Distant metastasis was the first site of disease progression in 10/17 (58.8%) patients who progressed. Significantly lower DFS was observed with invasion of adjacent structures (median DFS, 24 vs 6 months, log-rank p=0.003). Use of brachytherapy alone or after external beam yielded better DFS (median DFS, 24 vs 11 months, with vs without bracytherapy), yet this did not reach statistical significance, (log-rank p=0.06). A trend for better DFS was also observed for smaller tumour size (≤1.5cm), and EQD2 >70 Gy. Conclusion Approximately half of patients treated with salvage radiotherapy for recurrent endometrial cancer survive beyond 5 years. Disease progression usually occurs at distant sites. Poor outcome is predicted by non- endometrioid histology and advanced local disease. PO-1148 Implementation of a cervix cancer specific patient reported outcome measure in clinical practice S. Atallah 1 , L. Barbera 2 , M. Folwell 3 , D. Howell 4 , A. Liu 5 , C. Jennifer 6 1 Princess Margaret Cancer Centre- University Health Network, Department of Radiation Oncology- University of Toronto, Toronto, Canada ; 2 Cross Cancer Institute, Department of Oncology- University of Calgary, Toronto, Canada ; 3 Royal Victoria Regional Health Center, Department of Radiation Oncology- University of Toronto, Barrie, Canada ; 4 Princess Margaret Cancer Centre- University Health Network, Department of Psychosocial Oncology- University of Toronto, Toronto, Canada ; 5 Princess Margaret Cancer Centre- University Health Network, Department of Biostatistics- University of Toronto, Toronto, Canada ; 6 Princess Margaret Cancer Centre, Radiation Oncology, Toronto, Canada Purpose or Objective To evaluate implementation of a cervix cancer specific patient-reported outcome measure, the European Organization for Research and Treatment of Cancer Quality of Life Cervical Cancer module (EORTC QLQ-CX24), into gynecologic oncology clinics. Material and Methods This was a prospective, multi-institutional, cross-sectional study involving cervix cancer patients previously treated with curative intent radiotherapy who were attending routine follow-up appointments. Between January 2017

Purpose or Objective Treatment of locally advanced cervical cancer includes use of external beam radiotherapy (45-50Gy/25-28#) along with concurrent chemotherapy followed by high-dose-rate (HDR) brachytherapy. Treatment goal is to deliver an EQD2 radiotherapy dose of 85-90Gy. At present, grossly enlarged nodes tend to receive a sequential or simultaneous integrated tumoricidal boost dose of 55-60Gy. Dosimetric contribution to pelvic nodes is less certain with brachytherapy. Aim of the present study was to assess the dosimetric contribution of image-based HDR intracavitary brachytherapy (ICRT) to pelvic lymphnodes and to estimate its co-relation to Point-B dose. Material and Methods Between January’2018 - December’2018, fifty patients with locally advanced cervical cancer were enrolled in prospective observational study conducted at Rajiv Gandhi Cancer Institute and Research Centre, India. All patients had previously received intensity modulated radiotherapy (IMRT) to a dose of 45Gy/25# and was planned for three fractions of 3D-based high dose rate (HDR) brachytherapy. Three fractions of HDR brachytherapy to a dose of 7.5Gy/# to 90% high risk CTV (HR-CTV) were planned. CT scan with 3mm slice thickness for brachytherapy planning with IV contrast was taken. Pelvic nodal regions including external iliac (EIL), internal iliac (IIL), obturator and pre-sacral lymphnodes were delineated on the brachytherapy planning CT scan as per standard contouring guidelines. HR-CTV and intermediate risk CTV (IR-CTV) were additionally contoured. Brachytherapy planning was done and dosimetric assessment using dose volume histogram (DVH) was done. Mean dose to point B was recorded and correlated with pelvic nodal dose. Results High risk CTV volume received a mean dose of 7.52+0.56Gy per fraction to 90% volume. Maximal dose was received by bilateral obturator lymphnodal regions. Mean dose to EIL (Right 0.72+0.37, Left, 0.88+0.23), IIL (Right 1.37+0.55, Left, 1.32+0.46), obturator (Right 1.73+0.42, Left, 1.74+0.62) and presacral nodes (1.12+0.70) per fraction was noted. Mean dose to point B significantly differed from dose to pelvic nodes and showed a low degree of correlation. Also, approximately 35% of points B’s were located outside the pelvic lymphnodal regions. Conclusion Pelvic nodes tend to receive a significant dosimetric contribution from HDR image based brachytherapy. In order to decrease pelvic toxicity, this fact must be taken into account while planning intensity modulated radiotherapy boost to gross nodal disease. Also, Point B is a poor indicator of the dose delivered to the pelvic lymph nodes. PO-1147 Salvage radiotherapy for recurrent endometrial cancer: predictors of outcome. H. Almasri 1 , R. Cooper 1 , F. Slevin 1 , K. Cardale 1 1 Leeds teaching hospitals NHS trust, Radiation Oncology, Leeds, United Kingdom Purpose or Objective To evaluate the outcomes of patients treated with salvage radiotherapy for vaginal recurrence of endometrial cancer and analyse potential prognostic predictors. Material and Methods Medical records of 28 patients treated with salvage radiotherapy for biopsy-proven recurrent vaginal disease between 2012 and 2016 were retrospectively reviewed. All were initially treated with surgery without adjuvant pelvic radiotherapy. Patients’ age, initial stage, grade, histology, size of recurrent disease, whether or not it invaded adjacent organs and pelvic lymph node status were recorded as well as radiotherapy techniques and cumulative doses. Overall survival (OS), disease-free