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or not after SABR (2y, OS 87% vs 53%, p=0.02). 5y OS for patients treated for breast metastases was 88%, for colorectal cancer 52% and for NSCLC 62%. No significant differences on LC was detected between different primary tumors.LC rates appears relate only to BED value. Toxicity was mild and not exceeded the grade 2. Conclusion The SABR appears as safe and effective therapy with a good rate of LC of pulmonary metastases using BED value exceeding 100Gy ( only 36pts relapsed in the treatment field with a total number of 647 treated lesions) . The influence on OS appears to be related to the time of metastases appearance (synchronous vs metacronous), primary tumor controlled or not and the use of chemotherapy after SABR. The rate of OS, confirms the possibility to use of SABR with curative intent in well selected oligometastatic patients. The better rates of OS occurs in pts treated for breast and colorectal cancer. The majority of failures was represented by extra thoracic spread, leading to necessity of more effective systemic therapies. EP-1380 Can radiomic features describe lung semantic features in NSCLC patients? E.E.C. De Jong 1 , W. Van Elmpt 2 , S. Rizzo 3 , R.T.H. Leijenaar 1 , T. Refaee 1 , L.E.L. Hendriks 4 , B. Reymen 2 , A.M.C. Dingemans 4 , P. Lambin 1 1 Maastricht University Medical Centre, The D-lab: Decision Support for Precision Medicine- GROW-School for Oncology and Developmental Biology- Maastricht Comprehensive Cancer Centre, Maastricht, The Netherlands 2 Maastricht University Medical Centre, GROW-School for Oncology and Developmental Biology- Department of Radiation Oncology- MAASTRO Clinic, Maastricht, The Netherlands 3 European Institute of Oncology, Department of Radiology, Milan, Italy 4 Maastricht University Medical Centre, GROW-School for Oncology and Developmental Biology- Department of Pulmonology, Maastricht, The Netherlands Purpose or Objective Survival rates of lung cancer are still quite low. Finding patient specific tumor characteristics will lead to more personalized treatments. Qualitative image characteristics such as cavitation (see Figure 1), ground- glass opacity or air bronchogram, have been shown to be prognostic in non-small cell lung cancer (NSCLC). However, since these semantic features typically are not automatically calculated, they suffer from interobserver variability. Radiomic features may well describe these semantic features. Therefore, in this study, we developed a model to predict these semantic features based on a combination of quantitative radiomic features, which are automatically extracted from CT images.

Figure 1. Overall survival.

Conclusion In a cohort of biopsy-proven, relatively elderly patients with a strong representation of females and adenocarcinoma, stereotactic radiotherapy offers an excellent modality of treatment for local control for early stage non-small cell lung cancer in patients that are either unable or unwilling to undergo radical surgery. Our local control and survival rates compare favourably with published international series. EP-1379 stereotactic radiotherapy for oligometastases in the lung: analysis of 279 patients (647 lesions). F. Casamassima 1 , C. Menichelli 1 , G. Pastore 1 , A. Fanelli 1 1 Radioterapia Istituto Ecomedica, radiotherapy, Empoli, Italy Purpose or Objective The lung is a frequent site of metastases from solid tumors. Recent observations suggest the existence of a disease phase where metastatic diffusion stops leaving limited number of foci (oligometastatic state). Eradicative therapies of all these limited metastatic sites may have positive effects on disease progression and OS. For these purpose, patient selection and relationship with systemic therapies are very important. We study the results in term of LC, OS, toxicity and progression modalities in 279 patients treated with SABR for pulmonary oligometastases from different primary tumors. Material and Methods Between December 2010 and April 2016, 279 pts (172 male and 76 female) were treated by SABR on 647 lesions. Primary cancer was lung in 45%, colonrectal in 24%, breast in 5%, H&N in 3%, Kidney in 2,5% and 16% others. The histological type was Adenocarcinoma in 63%, Squamosus carcinoma in 20%, other in 17%. The median number of treated lesions in the same patients was 2 (range 1-5). Median target volume was 3,18 cc. The median dose of 33,2Gy was prescribed to 70% isodose with median BED to isocenter of 118Gy in 1 to 3 fx (median 1fx). Treatment was delivered by 6MV linac with beam modulator. Set up and isocenter position assessed by CBCT. Toxicity was evaluated using CTCAE vs2 Results With median follow up of 19 month (range3-56), median OS was 56m, DFS was 16m and median LC 18m. 36 pt relapsed in the treatment field, 74 pts in the chest and 219 showed extra pulmonary recurrences. Statistically signicative differences on OS was observed between patient with primary controlled or not (2y, OS 89% vs 61%; p=0.001), with metacronous vs synchronous metastases (2y, OS 98% vs 64%, p=0.001), chemotherapy