ESTRO 37 Abstract book

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ESTRO 37

commission on Radiation Units and Measurements (ICRU) and converted into EQD2 (α/β=3Gy). These parameters were examined as potential predictors of late toxicity, which was classified using Common Terminology Criteria for Adverse (CTCAE) v.4.0. Grade 2 urinary toxicity was the criteria. Univariate and multivariate analyses were conducted. Results Median follow-up was 4.9 years (4.5-5.3). Survival rates without grade 2+ urinary toxicity at 3 and 5 years were 69.8% (95%CI: 67.0-72.6) and 63.8% (95%CI: 60.7-66.9), respectively; and were 84.2% (95%CI: 81.8 - 86.6) and 78.5% (95%CI: 75.5-81.5) for patients without local relapse. Mean bladder D 2cm3 was 68.5Gy (interquartile [IQ]: 62.8–73.0). Dmean of bladder trigone was 60Gy (IQ: 54.7-65). After univariate analysis for 237 patients without local relapse, D 2cm3 was strongly associated with probability of urinary toxicity, which increased when D 2cm3 >70Gy (p=0.006). The effect was still higher for higher thresholds (p<0.001 for D 2cm3 >75Gy or >80Gy). ICRU bladder (p=0.021), D 0.1cm3 (p=0.018) and D 2cm3 (p=0.006) were significant, and volume of the bladder (p=0.068) was borderline. Using a cut-off of 65Gy, the mean bladder trigone dose correlated with urinary toxicities (p=0.007). There was a strong association between dosimetric parameters of the whole bladder and trigone (p<0.0001). In multivariate analysis, two parameters were associated with late grade 2+ urinary toxicity: 1/ bladder D 2cm3 , whatever the cut-off: >70Gy (HR=1.917; 95%CI 1.044–3.519) >75Gy (HR=2.483; 95%CI 1.300–4.742) or >80Gy (HR=3.814; 95%CI 1.752–8.301); and 2/ Dmean of the bladder trigone, with a cut-off 65Gy (HR = 2.031; 95%CI 1.023 – 4.033). Conclusion In this analysis based on a homogeneous cohort of patients, significant relationships were shown between bladder and trigone dose/volume parameters and probability of urinary toxicity. An increased risk was seen for bladder D2cm 3 >70Gy, suggesting that bladder sensitivity is higher than previously believed. Further studies are needed to validate these findings. OC-0072 Risk factors for ureteral stricture after IGABT in cervical cancer: results from the EMBRACE studies L.U. Fokdal 1 , K. Tanderup 1 , R. Pötter 2 , K. Kirchheiner 2 , A. Sturdza 2 , C. Chargari 3 , I. Jürgenliemk-Schulz 4 , B. Segedin 5 , L.T. Tan 6 , P. Hoskin 7 , U. Mahantshetty 8 , K. Bruheim 9 , B. Rai 10 , C. Kirisits 2 , J.C. Lindegaard 1 1 Aarhus University Hospital, Department of Oncology, Aarhus C, Denmark 2 Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria 3 Institute Gustave-Roussy, Department of Radiation Oncology, Paris, France 4 Utrecht University Hospital, Department of Radiation Oncology, Utrecht, The Netherlands 5 Institute of Oncology Ljubljana, Department of Oncology, Ljubljana, Slovenia 6 Addenbrooke’s Hospital- Cambridge University Hospitals, Departments of Oncology- Radiology and Gynae-oncology, Cambridge, United Kingdom 7 Mount Vernon Cancer Centre, Department of Radiation Oncology, Northwood, United Kingdom 8 Tata Memorial Hospital, Department of Radiation Oncology, Mumbai, India 9 Oslo University Hospital, Department of Radiation Oncology, Oslo, Norway 10 Regional Cancer Centre Chandigarh, Department of Radiation Oncology, Chandigar, India This abstract is part of the media programme and will be relased on the day of its presentation

Conclusion In this multicenter study on IGABT in vaginal cancer local control rates and severe bowel and bladder morbidity seem to compare favorably with published results from the radiographic era. To better understand the dose response and target volume relationships and to improve future outcomes in a (prospective) multicenter setting a common target concept for IGABT in vaginal cancer is essential. OC-0071 Bladder and bladder trigone dose/volume parameters: correlation with toxicity in cervical cancer E. Manea 1 , A. Escande 2 , S. Bockel 1 , F. Busato 1 , T. Kumar 1 , M. Laurans 1 , I. Dumas 1 , R. Mazeron Υ 1 , I. Lazarescu 1 , E. Deutsch 1 , C. Haie-Meder 1 , C. Chargari 1 1 Institut Gustave Roussy, Radiotherapy Department, Villejuif, France 2 Oscar Lambret Comprehensive Cancer Center, Radiotherapy Department, Lille, France Purpose or Objective To determine the correlation between dose volume parameters of the bladder and trigone bladder and late urinary toxicity in locally advanced cervical cancer patients treated with pulsed-dose-rate brachytherapy (PDR BT). Material and Methods 298 consecutive patients with International Federation of Gynecology and Obstetrics (FIGO) stage IB to IVA cervical carcinoma treated with concurrent chemo-radiation therapy and PDR BT from 2004-2015 were included. Dosimetric evaluation (D0.1cm 3 , D2cm 3 , D2cm 3 /pulse, D2 cm 3 , D1cm 3 /pulse, D1cm 3 , D0.5cm 3 /pulse, D0.5 cm 3 , Dmax/pulse, Dmax, Dmean/pulse, Dmean) and volumetric parameters (cm 3 ) of the whole bladder and trigone bladder were analyzed. Trigone was delineated as the triangular structure between the internal urethral orifice caudally and the two ureteral orifices cranially. Cumulative doses (including external beam radiotherapy contribution) were analyzed according to International