ESTRO 38 Abstract book

S644 ESTRO 38

radiation oncologist by clinical examination and laryngoscopy. CT-can was used when needed. Results One hundred thirty-eight (138) patients were included in this prospective cohort study from January 2005 to August 2017. Follow-up was closed in April 2018 (mean follow-up 78,11 ± 39,85 months, range 7 to 137 months, median 77 months). No one of the patients included were lost of follow-up until last visit or death. Seventy-one patients were treated by conventional schedules and sixty-seven by hypofractionated schedules. Patients characteristics for age, sex, alcohol and tobacco consumption were similar in both cohorts. All patients showed a complete clinical response after radiotherapy according to RECIST criteria. No differences were found for local relapse free survival (p=0,524)(Fig 1A), larynx preservation rate (p=0.933)(Fig 1B), disease recurrence (p=0,584)(Fig 1C) metastases (p=0,768)(Fig 1D) second primary tumours (p=0,895) or Overall Survival rates (p=0,70)between the two cohorts. Acute laringopharyngeal toxicity was higher in the hypofractionation group ( p = 0,004), mainly due to an increase in mild and moderate toxicity. Severe late laryngeal toxicity (oedema) was similar in both cohorts (p=0,714).

Bordeaux University Hospital, , with pre- and post-RT PET- scan were included. During RT, the variation in weight and the lumbar skeletal muscle index (SML) were studied according to oral nutrition, or use of feeding tube with preventive or curative intent. Sarcopenia was evaluated bySML calculated as the ratio of (L3 muscle surface) / (size)², on pre- and post-RT PET scans. Overall and progression free survival have been estimated by the Kaplan-Meier method and evaluated according to pre- and post-RT sarcopenia and type of nutrition. Results From 2011 to 2017, 124 patients were irradiated for oropharyngeal cancer and 116 (93%) had chemoradiotherapy. Median follow-up was 18.2 months [1.7-71.6]. At diagnosis, 55 ,patients (44%) were sarcopenic compared to 80 patients (65%) 3 months after RT (p <10 -6 ). Patients were less sarcopenic before treatment with p16+ oropharynx cancer than when with p16- oropharynx cancer: 28% vs 63% (p<0.001). Overall Survival was not significantly associated with pre-RT sarcopenia, [Hazard Ratio = 1.6; 95% CI = 0.77-3.2; p = 0.12], as well as PFS [HR = 0.57; 0.32-1.03; p = 0.052]. Patients lost less weight during RT with preventive feeding tube (mean weight loss :1.6 kg)) compared to curative feeding tube (5.6 kg) or exclusive oral nutrition (4.2 kg) (p = 0.003). The SML decreased significantly less in the case of preventive feeding tube (-4%) versus curative feeding tube (-12%) or exclusive oral nutrition (-8%) (p <0.001). Finally, OS [HR = 0.38; 0.18-0.81; p = 0.03] and PFS [HR = 0.45; 0.26-0.82; p = 0.02] were significantly associated with post-RT sarcopenia. At 2 years overall survival was 85% in non-sarcopenic patients after radiotherapy compared with 69% in sarcopenic patients after radiotherapy. Conclusion Evaluation of sarcopenia is relevant in oropharyngeal cancers. Preventive enteral nutrition,associated with decreased muscle mass or post-RT sarcopenia, is predictive of OS and PFS. EP-1163 Hypo vs conventional radiotherapy for T1 glottic cancer: A prospective cohort study B. Salas 1 , D.J. Domínguez Nuez 2 , R. Cabrera 1 , L. Ferrera 1 , M. Lloret 1 , P.C. Lara 3 1 Hospital Universitario de Gran Canaria Doctor Negrín., Radiation Oncology, Las Palmas de Gran Canaria, Spain ; 2 Universidad de Las Palmas de Gran Canaria, Medicine School. Radiation Oncology, Las Palmas de Gran Canaria, Spain ; 3 Hospital Universitario San Roque/ Universidad Fernando Pessoa Canarias, Oncology Department, Las Palmas de Gran Canaria, Spain Purpose or Objective The aim of the present study is to evaluate the clinical outcomes and toxicity rates of a series of prospectively followed patients suffering from squamous T1N0M0 glottic cancers treated either with conventional or hypofractionated radiotherapy schedules. Material and Methods From Jan 1 st ,2005 to August 1 st ,2017, T1N0M0 squamous glottic cancers treated by exclusive curative radiotherapy were included in this study. Patients were followed prospectively under our programme for Radiotherapy Quality Assurance. Curative radiotherapy was administered daily, 5/fr/week, either as a conventional fractionation schedule, with doses ranging from 1,8 to 2Gy per day, total dose of 70,2/70 Gy in 7 weeks or hypofractionated schedule with a dose from 2,2 to 2,25Gy per day, total dose 63,8/63Gy in 5,5 weeks. Fractionation schedule was chosen by the treating physician, according to his/her best knowledge. Stratification for fractionation schedule (conventional or hypofractionated) was predetermined in the study. Follow-up was performed by the referring otorhinolaryngologist and the treating

Figure 1

Conclusion In the present study, the hypofractionated schedule seems to be a feasible treatment option that have similar results than conventional fractionation treatment. Total treatment time saved (1.5w) at a cost of a moderate increase in mild toxicity is convenient for the patient and families. EP-1164 Estimated benefit of proton therapy and dose de-escalation in HPV p16-positive oropharyngeal cancer P. Brodin 1 , R. Kabarriti 2 , V. Gondi 3 , M. Pankuch 3 , M. Garg 2 , W. Tomé 2 1 Montefiore Medical Center/Albert Einstein College of Medicine, Radiation Oncology, Bronx, USA ; 2 Montefiore Medical Center, Radiation Oncology, Bronx, USA ; 3 Northwestern Medicine Chicago Proton Center, Radiation Oncology, Warrenville, USA Purpose or Objective Dose de-escalation strategies are being explored for oropharyngeal cancer (OPC) patients with good prognoses through human papilloma virus (HPV) p16-positive tumor biopsies. Here, we estimate the quality of life (QoL) benefit of proton therapy (PT) for different dose de- escalation levels for OPC, using a data-driven approach for estimating the QoL burden from normal tissue complications. Material and Methods The most recent normal tissue complication probability (NTCP) models for dysphagia, xerostomia, esophagitis,