ESTRO 2020 Abstract Book

S846 ESTRO 2020

AUC went up from 0.51/0.57 (clinical only), to 0.58/0.57 (+DVH) and 0.82/0.79 (clinical + DVH + radiomics). These trends were also confirmed by the AUCs of the final models evaluated in the testing cohort. For GI acute/late toxicities, the AUC for using only clinical parameters was 0.55/0.56, which increased to 0.56/0.55, and 0.78/0.85, when adding DVH or radiomics parameters respectively. For GU acute/late toxicities, the AUC went up from 0.55/0.67 (clinical only), to 0.62/0.67 (+DVH) and 0.72/0.73 (clinical + DVH + radiomics). For vaginal acute/late toxicities, the AUC went up from 0.54/0.58 (clinical only), to 0.53/0.53 (+DVH) and 0.74/0.76 (clinical + DVH + radiomics). Conclusion The predictive performance of NTCP models based on radiomics features is better than the commonly used DVH parameters. Dosimetric radiomics analysis is a promising tool for NTCP modelling in radiotherapy. PO-1563 New voxel-based approach to study the relation of tumor location and survival in NSCLC (SAKK- 16/00) D. Vuong 1 , M. Bogowicz 1 , J. Unkelbach 1 , S. Hillinger 2 , S. Thierstein 3 , E.I. Eboulet 3 , S. Peters 4 , M. Pless 5 , M. Guckenberger 1 , S. Tanadini-Lang 1 1 University Hospital Zurich and University of Zurich, Radiation Oncology, Zürich, Switzerland ; 2 University Hospital Zurich and University of Zurich, Thoracic Surgery, Zürich, Switzerland ; 3 Swiss Group for Clinical Cancer Research SAKK, Coordinating Center, Bern, Switzerland ; 4 Centre Hospitalier Universitaire Vaudois CHUV, Oncology, Lausanne, Switzerland ; 5 Kantonsspital Winterthur, Medical Oncology, Winterthur, Switzerland Purpose or Objective The anatomical location and extension of the primary lung tumor (PT) has shown prognostic value for outcome prediction, however was often quantified manually. We present an exploratory analysis of a new voxel-based approach to predict overall survival (OS) using the PT location for locally advanced non-small cell lung cancer (NSCLC). Material and Methods In total, 130 NSCLC patients from a prospective Swiss multi-centric randomized trial (IIIA/N2, SAKK-16/00, neoadj. chemo- or radiochemotherapy prior to surgery) were included. Pre-treatment CT scans were registered to a reference patient CT using an ipsilateral lung contour- only based deformable image registration and the ipsilateral main bronchus as a landmark (MIM Vista, 6.9.2.). An in-house software was developed to transfer each PT to a reference patient lung while maintaining the original PT shape. Two maps were created: (1) Frequency map representing anatomical locations of the PTs and (2) frequency weighted cumulative status (fwCS) map where PT location was uni-labeled with 2 yrs OS patient status (control:-1/no control:1). Both maps were created on a second internal dataset (n=28, IIIA/N2/IIIB NSCLC) to compare the cohorts. Nine anatomical non-overlapping lung regions were defined (2 cm from bronchi, heart, mediastinum and 1 cm from the chest wall divided into RL, AP and the rest lung region as peripheral). Mean fwCS values were calculated on those regions for both cohorts to identify risk areas. Additionally, for each patient of the internal cohort, 18 intensity features were extracted from the region of the SAKK fwCS map which was masked by the patient PT. An univariate logistic regression was performed and the performance was quantified using the area under the roc curve (AUC) with the 2 yrs OS as an endpoint.

Conclusion We demonstrated that RF trained on preselected radiomic features could potentially predict the stage of NSCLC. Further investigation with different MLM and more data will be done. PO-1562 Radiomics applied to dose distributions to predict toxicity after radiotherapy in cervical cancer F. Lucia 1 , V. Bourbonne 1 , G. Dissaux 1 , O. Miranda 1 , G. Dissaux 1 , U. Schick 1 , D. Visvikis 2 , J. Bert 2 , M. Hatt 2 , R. Abgral 3 1 Radiation Oncology department- University Hospital- Brest- France, Radiation Oncology department- University Hospital- Brest- France, Brest, France ; 2 LaTIM- INSERM- UMR 1101- Univ Brest- Brest- France, LaTIM- INSERM- UMR 1101- Univ Brest- Brest- France, Brest, France ; 3 Nuclear Medicine department- University Hospital- Brest- France, Nuclear Medicine department- University Hospital- Brest- France, Brest, France Purpose or Objective Dose-volume histograms (DVH) do not account for the spatial distributions of dose at the voxel level. Our goal was to compare the prediction of toxicity events after radiotherapy for locally advanced cervical cancer (LACC), relying on either DVH parameters or the use of the radiomics approach applied todose maps at the voxel level. Material and Methods Acute and late toxicity scores using the CTCAE v4, spatial dose distributions, and usual clinical predictors for toxicity, such as age and baseline symptoms, of 102 patients treated with chemoradiotherapy followed by brachytherapy for LACC were used in this study. Patients were split into training (patients treated in Brest, n=52) and testing (patients treated in Quimper, n=50) sets. In addition to usual DVH parameters, 91radiomic features (intensity and texture) of rectum, bladder and vaginal 3D dose distributions (defined using the organs at risk contours from the planning) were extracted after discretization into fixed bin width of 55 Gy, and evaluated for predictive modelling of gastrointestinal (GI), genitourinary (GU) and vaginal toxicities. Logistic Normal Tissue Complication Probability (NTCP) models were derived, using only clinical parameters, clinical + DVH, clinical + radiomics, DVH + radiomics and clinical + DVH + radiomics combinations. Results In the entire cohort (training/testing), the cumulative rates of acute and late grade ≥2 GU, GI and vaginal toxicities were 39%/42%, 14%/16%, 26%/28%, 10%/14%, 24%/24%, and 24%/24%, respectively. In the training cohort, for GI acute/late toxicities, the area under the curve (AUC) using only clinical parameters was 0.53/0.65, which increased to 0.66/0.63, and 0.76/0.87, when adding DVH or radiomics parameters respectively. For GU acute/late toxicities, the AUC went up from 0.55/0.56 (clinical only), to 0.84/0.90 (+DVH) and 0.83/0.96 (clinical + DVH + radiomics). For vaginal acute/late toxicities, the