ESTRO 38 Abstract book

S750 ESTRO 38

respectively. The replanning has been performed at a median dose of 45Gy. Median CTV at replanning volume

EP-1373 Introducing PET CT in SBRT lung cancer follow-up: Preliminary results of our center protocol. J. Luna 1 , D. Gonsalves 1 , L. Guzman 1 , M. Rincón 2 , M. Montero 1 , A. Ilundain 1 , W. Vasquez 1 , M.E. Lopez 1 1 Fundación Jiménez diaz, Radiation Oncology, Madrid, Spain ; 2 Fundación Jiménez diaz, Physics Radiation Oncology, Madrid, Spain Purpose or Objective To describe the preliminary results conducted for a follow- up protocol in primary lung cancer with stereotactic body radiation therapy in our center. The primary end point for this prospective study is to describe the morphologic and metabolic changes documented in the follow up with Positron emission tomography scan (PET CT) and the clinical decisions surrounding it. Material and Methods A multidisciplinary team consisted in radiation oncologist, radiologist and nuclear medicine specialist developed in 2014 a protocol for follow up in patients treated with SBRT for the lung cancer. A Tomography (CT) and PETCT have to be present at the diagnoses. SBRT treatment consisted in a 4D CT simulation scans with an Elekta frame based immobilization system and free breathing. The plan was delivered using Beam Modulator Linac with HEXA POD system and ELEKTA XVI CBCT system for quality assurance. Fractioning was determining by physician criteria. Our follow-up included a CT scan at 2 months post treatment, then 2-3 months a PETCT and a second PETCT 2 month later for confirmation of results. After these first three studies, if the patient presented a complete response (1º arm), as determine in the PERCIST 1.1 (PET Response Criteria in Solid Tumors), a CT every 6 months for the first 3 years were done. If the patient presented a partial response or stable (2ºarm), a follow up with PETCT was done every 6 months for the first 3 years. It was recommended in 1º arm that a progression had to be confirmed with a PET and in the 2º arm two possible options were available: a PETCT in 3 months or a biopsy. We reviewed the clinical records from the patients involved in the study between April 2015 and November 2017 and analyzed local control rate (LC),loco regional progression(PLR) and systemic progression rate(PSR). Results We enrolled 31 patients. 77.4 % were men. The median age was 73 years (range 61-81 years). The localization for the tumor was 61 % peripheral, 22.5% central and 16.4% ultra central. The mean size of the tumor treated was 19.5 mm and with mean SUV max of 11.36(sux max1.4 - 31.7). The most frequent fraction prescription was 5 session of 10 Gy per session. The patients included in 1º arm follow up were 9.6%. Median follow up of 19.22 months. LC was 96.8 %, PSR 16.4% and PLR 9.6%. In 1º arm follow up, 2 patients presented a local progression with a complete response in PET CT. In 2º arm, 3 patients went for lung biopsy because a disease progression with a negative results afterwards. In both arms, 3 patients presented a radiological regional progression (lymph node ipsilateral) diagnosed in PET went for biopsy: 2 were negative and 1 positive Conclusion In our preliminary results, PET is useful to determine a morphologic and metabolic response in SBRT. Developing a follow up protocol including PETCT for SBRT allows a homogeneity approach to clinical decisions. EP-1374 ECOG-PS and its changes in inoperable stage III NSCLC patients treated with chemoradiotherapy L. Käsmann 1 , J. Taugner 1 , C. Eze 1 , M. Dantes 1 , O. Roengvoraphoj 1 , K. Gennen 1 , M. Karin 1 , A. Tufman 2 , M.

was 74.7 cc Conclusion

Tumor shrinkage is common during RCT in NSCLC. There are points in time during the treatment course when it may be appropriate to adapt the plan to improve sparing of normal tissues. In our patients population in which an adaptive replanning was performed we early observed a tumor reduction (13% after 2 weeks of treatment). We are trying to understand if there are volume reduction patterns that can influence prognosis and therefore help to classify lung neoplasms in different groups EP-1372 External Validation of a Survival Score for Limited Disease Small Cell Lung Cancer (LD-SCLC) L. Käsmann 1 , R. Abdo 1 , C. Eze 1 , M. Dantes 1 , J. Taugner 1 , K. Gennen 1 , O. Roengvoraphoj 1 , D. Rades 2 , M. Niyazi 1 , C. Belka 1 , F. Manapov 1 1 LMU University Hospital Grosshadern, Department of Radiation Oncology, Munich, Germany ; 2 University of Luebeck, Department of Radiation Oncology, Luebeck, Germany Purpose or Objective Definitive chemoradiotherapy is the standard treatment for limited disease small cell lung cancer (LD-SCLC). However, median survival in LD-SCLC ranges between 16 and 24 months due to early locoregional failure and metastases and not all patients can tolerate such intensive regimen. Defined subgroups such as patients in reduced health condition, with severe comorbidities or elderly need to be critical considered before treatment allocation. Patients with a poor survival prognosis should be offered a short course of treatment to avoid spending a substantial proportion of their limited remaining time with receiving chemoradiotherapy. In order to personalize treatment regimens a survival score for these patients was developed. The aim of this study is to validate the survival score for LD-SCLC in an independent patient collective. Material and Methods We collected data of all patients treated with chemoradiotherapy (CRT) for LD-SCLC between 2004 and 2015. The validation cohort of this study included 78 patients. 38% of all patients were treated with concurrent CRT. The survival score was calculated by independent prognostic factors namely gender, Karnofsky performance status (50-70 versus 80-100%), Tumor substage (very limited disease versus limited disease) and hemoglobin level before radiotherapy (< 12 mg/dl versus ≥ 12 mg/dl). Scoring points were derived from 2-year survival rates divided by 10 and added to scores for individual patients. Three groups were formed (9-13, 14-18 and 19-26 points). The 2-year survival rate of each group from the original study was compared to its corresponding group from this validation study. Results Median survival time in our patient collective is 17 months (range: 1-123months). 1- and 2-year-survival rates are 60% and 36%. In the current validation study, the 2-year survival rates were 0% in the 9-13 points group, 35% in the 14-18 points group and 43% in the 19-26 points group, respectively (p=0.018). The difference in 2-year survival between the 9-13 points and the 14-18 points group was significant in the complete cohort (p=0.007) as well after stratification of concurrent CRT in the validation cohort (p<0.001), whereas the difference between the 14-18 points and the 19-26 points group was not (p=0.602, p=0.770). Conclusion The score was reproducible and valid to estimate the 2- year survival rate of patients with LD-SCLC. In order to improve the differentiation between patients with an intermediate and a favorable survival prognosis, the scoring system needs further development.