Abstract Book

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among the possible prognostic factors. Conclusion

this analysis we focused on the changes in Hounsfield units (ΔHU) and the correlation with the corresponding

The solid component diameter was the only prognostic factor for patients with stage I NSCLC when intensity- modulated SBRT was performed. This finding appears important to select patients for dose escalation. EP-1356 Radical Accelerated Hypofractionated 3d-CRT In NSCLC Patients on behalf of GOECP-SEOR. N. Rodriguez De Dios 1 , E. Sanchez 2 , A. Otero 3 , J. Lopez 4 , J. Luna 5 , R. Delgado 6 , M. López 7 , E. Cenizo 8 , J. Monroy 9 1 Hospital del Mar, Radiation Oncology, Barcelona, Spain 2 complejo Hospitalario León, Radation Oncology, León, Spain 3 hospital Clínico Universitario Virgen De La Victoria, Malaga, Spain 4 hospital Universitario Virgen Del Rocío, Sevilla, Spain 5 hospital Universitario Fundación Jiménez Díaz, Madrid, Spain 6 complejo Hospitalario Carlos Haya, Málaga, Spain 7 hospital Clínico Lozano Blesa, Radiation Oncology, Zaragoza, Spain 8 complejo Hospitalario León, León, Spain 9 hospital Universitario De La Ribera, Alcira, Spain Purpose or Objective Increasing the radiotherapy dose can result in improved local control for non-small-cell lung cancer (NSCLC) and can thereby improve survival. This can be compromised by accelerated repopulation of tumour cells during radiotherapy. Accelerated hypofractionated radiotherapy (AHRT) can expose tumors to a high dose of radiation in a short period of time. To describe the outcome of treating early-stage (T1-3N0) non–small-cell lung cancer (NSCLC) with AHRT Material and Methods We identified 103 patients. Mean age was 78.8 ± 7.9 years. Most patients were male (85.4%) and had performance status (PS) ≥ 2 in 45.6% of cases. The AHRT mean dose/fraction, total dose, and number of fractions were 2.87 Gy, 61 Gy, and 19, respectively. Three groups of doses were defined according to BED 10 : ≥ 75 Gy, 61-74 Gy and ≤ 60 Gy. Results After a median follow-up of 30 months, the 1 and 3 years overall survival (OS) was 82.0 and 40.4%. Cause specific survival (CSS) was 89.6 and 63.0%. On multivariate Cox regression analysis, tumor size was an independent risk factor for OS (p=0.01) and CSS (p=0.02). PS ≥ 2 was an independent risk factor for OS (p =0.02). The major acute adverse reactions were grade 2 dermitis (9.7%), grade 2 esophagitis (3.8%) and grade 3 pneumonitis (1%). There were 2 patients with grade 2 late pneumonitis. Conclusion AHRT is a reasonable alternative to conventional fractionated radiotherapy in stage I-II NSCLC without access to SBRT. Tumor size and PS ≥ 2 were independent risk factors for survival. EP-1357 Changes of lung density after radiotherapy for thoracic carcinomas–an analysis of follow up CT scans C. Schröder 1 , R. Engenhart-Cabillic 2 , H. Vorwerk 2 , S. Kirschner 3 , E. Blank 3 , D. Sidow 3 , A. Buchali 3 1 Universitätsspital Zürich, Klinik für Radio-Onkologie, Zürich, Switzerland 2 University Clinic Giessen and Marburg, Clinic for Radiotherapy and Radiation Oncology, Marburg, Germany 3 Ruppiner Kliniken GmbH, Clinic for Radiotherapy and Radiation Oncology, Neuruppin, Germany Purpose or Objective An objective way to qualify the effect of radiotherapy (RT) on lung tissue is the analysis of CT scans after RT. In

radiation dose after RT. Material and Methods

Follow-up CT data of patients that received radio- (chemo-)therapy for thoracic carcinomas was available for 61 patients 12 weeks after therapy and 51 patients 6 months after therapy. Pre- and post-RT CT scans were matched and ΔHU was calculated using customized research software. ΔHU was calculated in 5-Gy-intervals and the correlation between ΔHU and the corresponding dose was calculated as well as the regression coefficients. Additionally the mean ΔHU and ΔHU in 5-Gy- intervals were calculated for each tumor entity. Results The mean density changes at 12 weeks and 6 months post RT were 28,16 HU and 32,83 HU. The correlation coefficient between radiation dose and ΔHU for all available values was 0,162 (p=0,000). When looking at 12 weeks and 6 months individually the coefficients were 0,166 (p=0,000) and 0,158 (p=0,000). The resulting regression coefficient was 1,516 HU/Gy (p=0,000) for all values and 1,439 HU/Gy (p=0,000) and 1,612 HU/Gy (p=0,000) at 12 weeks and 6 months. The individual regression coefficients for each patient range from -2,23 HU/Gy to 7,46 HU/Gy at 12 weeks and -0,45 HU/Gy to 10,51 HU/Gy at 6 months. When looking at the three tumor entities individually the highest ΔHU at 12 weeks was seen in patients with SCLC (38,13 HU) and at 6 month in those with esophageal carcinomas (40,98 HU). Conclusion For most dose intervals there was an increase of ΔHU with an increased radiation dose. This is reflected by a statistically significant, although low correlation coefficient. The regression coefficients of all patients show large interindividual differences. EP-1358 Correlation between changes in lung function and lung density after radiotherapy for thoracic cancer C. Schröder 1 , R. Engehart-Cabillic 2 , H. Vorwerk 2 , M. Schmidt 3 , W. Huhnt 3 , E. Blank 3 , D. Sidow 3 , S. Kirschner 3 , A. Buchali 3 1 University Hospital Zürich, Clinic for Radiation Oncology, Zürich, Switzerland 2 University Clinic Giessen and Marburg, Clinic for Radiotherapy and Radiation Oncology, Marburg, Germany 3 Ruppiner Kliniken GmbH, Department of Radiation Oncology, Neuruppin, Germany Purpose or Objective In this analysis we focused on the correlation of a patients’ lung function (PFT) data and lung density changes (ΔHU) detected in follow up CTs in patients after high dose radio-chemotherapy of intrathoracic carcinomas. Material and Methods PFT and lung function data was available for 58 patients 12 weeks and 47 patients 6 months after radio-(chemo- )therapy for thoracic carcinomas (NSCLC, SCLC and esophageal carcinoma). NSCLC patients were treated with a total radiation dose of 74 Gy, SCLC patients with 60 Gy and patients with esophageal carcinoma with 66 Gy. Fraction dose was 2 Gy each. Eligible patients received chemotherapy according to intradepartmental standards. All patients completed the treatment protocol. Patients received follow up CT scans 12 weeks and 6 months after RT which were matched with the planning CT scans of each patient and then subtracted to calculate ΔHU for each voxel using customized research software. PFT data regarding e.g. vital capacity (VC), total lung capacity (TLC) and diffusion capacity for carbon monoxide (DLCO) were collected before and at several follow up appointments after treatment.