ESTRO 36 Abstract Book

S645 ESTRO 36 2017 _______________________________________________________________________________________________

Marburg, Marburg, Germany 3 Ruppiner Kliniken GmbH, Klinik für Strahlentherapie und Radioonkologie, Neuruppin, Germany Purpose or Objective There are numerous ways to examine radiation therapy (RT) related injuries to the lung tissue. Next to obvious factors like treatment induced side effects, the changes in pulmonary function are a simple way to quantify the effects of RT on a patient’s lung. In this study we prospectively collected patient-related, dose-related and PFT data before RT and at several follow up visits after RT to analyze the time course of PFT changes and influencing factors. Material and Methods From 04/12 to 10/15 81 patients with NSCLC, SCLC or esophageal carcinoma where treated with high dose radiation therapy. Patients with NSCLC where treated with a total dose of 74 Gy, those with SCLC with 60 Gy and those with esophageal tumors with 66 Gy. Fraction dose was 2 Gy each. Patients were treated with or without concurrent or sequential chemotherapy according ti intradepartmental standards. Data regarding PFT (ventilation and diffusion parameters) was collected before treatment, 6 weeks, 12 weeks and 6 months after RT. The following lung function parameters were analyzed: vital capacity (VC), total lung capacity (TLC), forced expiratory volume in 1 second (FEV1), diffusion capacity for carbon monoxide (DLCO) and capillary blood gas analysis. Additionally the influence of patient and treatment related factors on PFT was analyzed. Results The mean FEV1 constantly declined during the follow up (p = 0,001). In total 68 % of patients had a reduced FEV1 at 6 months. The general linear model (GLM) with repeated measures determined that the FEV1 differed statistically significant over time (p = 0,001). The mean VC didn’t change during the follow up (p > 0,05). The mean TLC showed a constant decline after RT (p = 0,026). At 6 months 60 % of patients showed a decline in VC and 73 % in TLC. The GLM revealed no significant changes of the VC over time. There was a difference between the TLC before RT and at 6 months post RT (p = 0,026). The mean DLCO had declined at 6 and 12 weeks but showed a slight recovery at 6 months (p < 0,0005). At 6 months 86 % of patients had a reduced DLCO. The GLM determined that there where statistically significant differences of the DLCO over time (p < 0,0005). There was an increase in pCO2 and a decrease in pO2 after treatment (p > 0,05). At 6 months approximately 60 % had a decline in pO2 and an increase in pCO2. Only the pre-treatment PFT classification had a significant influence on the FEV1 after RT. The GLM determined no statistically significant changes of the blood gas parameters over time. Only the pre-treatment PFT classification had a significant influence on the FEV1 after RT. Conclusion The DLCO seems to be the most reliable indicator for lung tissue damage after thoracic radiotherapy. Although there might be some significance ventilation parameters appear to be less reliable. Only the pre-treatment PFT classification had a significant influence on the FEV1 after RT. EP-1204 Treatment Outcomes and Patterns of Radiologic Injury after Tomotherapy-based SBRT for Lung Tumours S. Arcangeli 1 , L. Falcinelli 2 , S. Bracci 3 , A. Greco 3 , A. Monaco 1 , J. Dognini 1 , C. Chiostrini 1 , R. Bellavita 2 , C. Aristei 2 , V. Donato 1 1 San Camillo-Forlanini Hospitals, Radiation Oncology, Rome, Italy 2 S. Maria della Misericordia University Hospital, Radiation Oncology, Perugia, Italy

overall survival compared with RT, including CFRT and SBRT. Considering the strength of the evidence, additional randomized controlled trials are needed before each treatment modality can be recommended routinely. EP-1202 A lot to a little or a little to a lot - dose- volume relationships in thoracic tumors C. Schröder 1 , R. Engenhart-Cabillic 2 , A. Buchali 3 1 Universität Giessen, Klinik für Strahlentherapie und Radioonkologie- Universitätsklinikum Giessen und Marburg, Giessen, Germany 2 Universität Marburg, Marburg, Germany 3 Ruppiner Kliniken GmbH, Klinik für Strahlentherapie und Radioonkologie, Neuruppin, Germany Purpose or Objective The purpose of this prospective randomized trial was to determine which constellation of dose and corresponding volume of the lung tissue as seen in the dose-volume- histogram (DVH) - either a lot to a little or a little to a lot - should be preferred to ensure the best possible outcome for patients with thoracic carcinomas. To ensure a wider approach we focused on both objective and subjective parameters like clinical outcome, changes in pulmonary function tests (PFT), radiological changes and quality of life (QoL). Material and Methods From 04/12 to 10/15 81 patients with NSCLC, SCLC or esophageal carcinoma were randomized and treated with either a 4-field-IMRT (Arm A) or a VMAT (Arm B) technique. Patients with NSCLC were treated with a total dose of 74 Gy, those with SCLC with 60 Gy and those with esophageal tumors with 66 Gy. Fraction dose/day was 2 Gy each. Patients were treated with or without concurrent or sequential chemotherapy according to intradepartmental standards. Data regarding clinical outcome (survival, side effects, local and distant control), PFT (ventilation and diffusion parameters) and quality of life (EORTC QLQ-C30 and QLQ-LC13) were collected before RT, 6 weeks, 12 weeks and 6 months after treatment. QoL data was additionally collected 1 year post RT. Radiological follow- up via CT focusing on lung density changes was done 12 weeks and 6 months after RT. Results The median follow up was 34,5 weeks. There was no significant difference regarding the local (p = 0,954) and distant (p = 0,206) outcome, side effects (all p > 0,05) or survival (p = 0,633) of patients in the two treatment arms at any follow up appointment. The comparison of the PFT showed a statistically significant difference for the DLCO 6 weeks post RT (p = 0,028). All other parameters did not differ significantly at any follow up appointment. Regarding the QoL there was no statistically significant difference between the summarized value for the QLQ- C30 and the QLQ-LC13 at any follow up appointment (p > 0,1). There was a statistically significant difference between the mean density of the lung parenchyma at 12 weeks (p < 0,0005) and 6 months post RT (p < 0,0005). Conclusion Since there was no significant and relevant difference between both treatment arms regarding PFT, clinical outcome and QoL it doesn’t seem to relevant how the DVH is shaped exactly as long as certain established dose constrains are respected. As to whether the difference between the CT density changes is not only significant but also clinically relevant further analysis is needed. EP-1203 Changes in pulmonary function after high dose intrathoracic radio(-chemo)therapy up to 74 Gy C. Schröder 1 , R. Engenhart-Cabillic 2 , A. Buchali 3 1 Universität Giessen, Klinik für Strahlentherapie und Radioonkologie- Universitätsklinikum Giessen und Marburg, Giessen, Germany 2 Universität Marburg, Klinik für Strahlentherapie und Radioonkologie- Universitätsklinikum Giessen und